Optimize Nokogiri search for post-processing pipeline [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

• Contributes to #271242 (closed)
• FF issue: #328696 (closed)

Problem

doc.search(...) operation has a bad performance for complex html documents with many elements.

Solution

Avoid unnecessary doc.search calls.

1. Combine multiple search operations
2. Share calculated result between several filters

Screenshots (strongly suggested)

I tested the performance locally with provided worst case.

Before	After
1.48367	0.38897
0.61317	0.48994
0.56842	0.37986
0.58618	0.36526
0.64647	0.44602
0.63078	0.47386
0.62561	0.35649
0.63586	0.43862
0.6167	0.43969
0.63569	0.40646
AVG	AVG
0.704	0.418

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because of feature flag.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team