Leaving a trailing slash in the context option causes the jira-ruby
gem to add an extra slash in HTTP requests to the URL, preventing
JIRA from working properly.

Closes #42494

Adds a rubocop rule (with autocorrect) to ensure line break after guard clauses.

Add OpenSSL::SSL::SSLError to rescue in JiraService & IssueTrackerService. This
will prevent an exception in production and instead display
a message to the user.

Use the EnforcedStyleForMultiline: no_comma option.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

The implicit interface of project services states that the "execute"
method is meant to be called when project hooks are executed.
Currently JiraService does not support any project events even though
JiraService#supported_events says that "commit" and "merge_request"
are supported. They are only used to render correct options in
JIRA configuration screen, but they are not supported.
Because of that, this commit makes "execute" method a no-op.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Code improvements, bug fixes, finish documentation and specs