Cast ENV['RSPEC_PROFILING_POSTGRES_URL'] to symbol in establish_connection call …

What does this MR do?

Casts ENV['RSPEC_PROFILING_POSTGRES_URL'] to symbol in establish_connection call.

DEPRECATION WARNING: Passing a string to ActiveRecord::Base.establish_connection for a configuration lookup is deprecated, please pass a symbol (:"") instead. (called from establish_connection at /builds/gitlab-org/gitlab-ce/config/initializers/rspec_profiling.rb:4)

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

config/initializers/rspec_profiling.rb

 module RspecProfilingExt
   module PSQL
     def establish_connection
-      ::RspecProfiling::Collectors::PSQL::Result.establish_connection(ENV['RSPEC_PROFILING_POSTGRES_URL'])
+      ::RspecProfiling::Collectors::PSQL::Result.establish_connection(ENV['RSPEC_PROFILING_POSTGRES_URL'].to_sym)
     end
   end