Update relate/unrelate note icons via @hazelyang

https://gitlab.com/gitlab-org/gitlab-ee/issues/2001#note_31580383

app/helpers/system_note_helper.rb

@@ -21,8 +21,8 @@ module SystemNoteHelper
     'outdated' => 'icon_edit',
     'approved' => 'icon_check',
     'unapproved' => 'icon_fa_close',
-    'relate' => 'icon_link',
-    'unrelate' => 'icon_chain_broken'
+    'relate' => 'icon_anchor',
+    'unrelate' => 'icon_anchor_broken'
   }.freeze
   def icon_for_system_note(note)

app/views/shared/icons/_icon_anchor.svg

+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill-rule="evenodd" d="m8.419 7.99l-.002.002c-.023-.026-.046-.051-.071-.075-.642-.642-1.678-.651-2.312-.018l-2.432 2.432c-.635.635-.626 1.668.018 2.312.642.642 1.678.651 2.312.018l1.028-1.028c.719.366 1.481.518 2.176.444l-1.753 1.753c-1.344 1.344-3.542 1.326-4.909-.041-1.367-1.367-1.383-3.566-.041-4.909l2.292-2.292c1.344-1.344 3.542-1.326 4.909.041.016.016.032.032.048.049.009.008.017.016.025.024.362.362.367.944.011 1.3-.356.356-.938.351-1.3-.011m-.575.284l.002-.002c.023.026.046.051.071.075.642.642 1.678.651 2.312.018l2.432-2.432c.635-.635.626-1.668-.018-2.312-.642-.642-1.678-.651-2.312-.018l-1.028 1.028c-.719-.366-1.481-.518-2.176-.444l1.753-1.753c1.344-1.344 3.542-1.326 4.909.041 1.367 1.367 1.383 3.566.041 4.909l-2.292 2.292c-1.344 1.344-3.542 1.326-4.909-.041-.016-.016-.032-.032-.048-.049-.009-.008-.017-.016-.025-.024-.362-.362-.367-.944-.011-1.3.356-.356.938-.351 1.3.011"/></svg>

app/views/shared/icons/_icon_anchor_broken.svg

+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><g fill-rule="evenodd"><path fill-rule="nonzero" d="M11.3 8.85c.2-.15.4-.3.6-.5l1.4-1.4c1.37-1.38 1.53-3.44.36-4.6-1.17-1.18-3.23-1.02-4.6.35l-1.4 1.4c-.2.2-.36.4-.5.6l1.66.66.04-.04 1.4-1.4c.6-.6 1.48-.66 1.98-.16s.44 1.38-.15 1.97l-1.44 1.4-.04.05.66 1.67zM8.85 11.3c-.15.2-.3.4-.5.6l-1.4 1.4c-1.38 1.37-3.44 1.53-4.6.36-1.18-1.17-1.02-3.23.35-4.6l1.4-1.4c.2-.2.4-.36.6-.5l.66 1.66-.04.04-1.4 1.4c-.6.6-.66 1.48-.16 1.98s1.38.44 1.97-.15l1.4-1.44.05-.04 1.67.66z"/><path d="M12.66 9.2h2c.27 0 .5.23.5.5v.06c0 .27-.23.5-.5.5h-2c-.28 0-.5-.23-.5-.5V9.7c0-.27.22-.5.5-.5zm-.4 2.12l1.43 1.42c.16.2.16.5 0 .7l-.07.04c-.2.2-.5.2-.7 0l-1.42-1.4c-.2-.2-.2-.53 0-.72l.05-.04c.2-.2.5-.2.7 0zm-2.8 1.1c0-.28.2-.5.5-.5H10c.28 0 .5.22.5.5v2c0 .27-.22.5-.5.5h-.05c-.28 0-.5-.23-.5-.5v-2zM6.7 3.24v-2c0-.27-.22-.5-.5-.5h-.05c-.27 0-.5.23-.5.5v2c0 .28.23.5.5.5h.05c.28 0 .5-.22.5-.5zm-2.1.4L3.16 2.2c-.2-.2-.5-.2-.7 0l-.04.04c-.2.2-.2.5 0 .7l1.4 1.42c.2.2.52.2.72 0l.04-.04c.18-.2.18-.5 0-.7zm-1.1 2.8c.27 0 .5-.2.5-.5V5.9c0-.27-.23-.5-.5-.5h-2c-.28 0-.5.23-.5.5v.06c0 .28.22.5.5.5h2z"/></g></svg>

app/views/shared/icons/_icon_chain_broken.svg

-<svg width="1792" height="1792" viewBox="0 0 1792 1792" xmlns="http://www.w3.org/2000/svg"><path d="M503 1271l-256 256q-11 9-23 9t-23-9q-9-10-9-23t9-23l256-256q10-9 23-9t23 9q9 10 9 23t-9 23zm169 41v320q0 14-9 23t-23 9-23-9-9-23v-320q0-14 9-23t23-9 23 9 9 23zm-224-224q0 14-9 23t-23 9h-320q-14 0-23-9t-9-23 9-23 23-9h320q14 0 23 9t9 23zm1264 128q0 120-85 203l-147 146q-83 83-203 83-121 0-204-85l-334-335q-21-21-42-56l239-18 273 274q27 27 68 27.5t68-26.5l147-146q28-28 28-67 0-40-28-68l-274-275 18-239q35 21 56 42l336 336q84 86 84 204zm-617-724l-239 18-273-274q-28-28-68-28-39 0-68 27l-147 146q-28 28-28 67 0 40 28 68l274 274-18 240q-35-21-56-42l-336-336q-84-86-84-204 0-120 85-203l147-146q83-83 203-83 121 0 204 85l334 335q21 21 42 56zm633 84q0 14-9 23t-23 9h-320q-14 0-23-9t-9-23 9-23 23-9h320q14 0 23 9t9 23zm-544-544v320q0 14-9 23t-23 9-23-9-9-23v-320q0-14 9-23t23-9 23 9 9 23zm407 151l-256 256q-11 9-23 9t-23-9q-9-10-9-23t9-23l256-256q10-9 23-9t23 9q9 10 9 23t-9 23z"/></svg>

app/views/shared/icons/_icon_link.svg

-<svg width="1792" height="1792" viewBox="0 0 1792 1792" xmlns="http://www.w3.org/2000/svg"><path d="M1520 1216q0-40-28-68l-208-208q-28-28-68-28-42 0-72 32 3 3 19 18.5t21.5 21.5 15 19 13 25.5 3.5 27.5q0 40-28 68t-68 28q-15 0-27.5-3.5t-25.5-13-19-15-21.5-21.5-18.5-19q-33 31-33 73 0 40 28 68l206 207q27 27 68 27 40 0 68-26l147-146q28-28 28-67zm-703-705q0-40-28-68l-206-207q-28-28-68-28-39 0-68 27l-147 146q-28 28-28 67 0 40 28 68l208 208q27 27 68 27 42 0 72-31-3-3-19-18.5t-21.5-21.5-15-19-13-25.5-3.5-27.5q0-40 28-68t68-28q15 0 27.5 3.5t25.5 13 19 15 21.5 21.5 18.5 19q33-31 33-73zm895 705q0 120-85 203l-147 146q-83 83-203 83-121 0-204-85l-206-207q-83-83-83-203 0-123 88-209l-88-88q-86 88-208 88-120 0-204-84l-208-208q-84-84-84-204t85-203l147-146q83-83 203-83 121 0 204 85l206 207q83 83 83 203 0 123-88 209l88 88q86-88 208-88 120 0 204 84l208 208q84 84 84 204z"/></svg>