Closes #6604 Add fetch priority to LCP when url is relative

[Khadreal]

Description

Fixes #6604

Documentation

Modify the regex pattern, to capture all possible cases, absolute, relative and other valid urls

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• [x] Bug fix (non-breaking change which fixes an issue).

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Coverage summary from Codacy

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Coverage variation	Diff coverage
Report missing for 2b088a335a85cb013d8186d2fc7e36f28d152c29[^1]	:white_check_mark: 100.00% (target: 50.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (2b088a335a85cb013d8186d2fc7e36f28d152c29)	Report Missing	Report Missing	Report Missing
Head commit (975369e1b9f790aa7e933814b3654f70eb8f77b2)	37190	14427	38.79%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#6626)	10	10	100.00%

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[Mai-Saad]

@Khadreal thanks for the PR. Working for the main shared template, and not adding fetchpriority in some edge cases as per exploratory testing below (not working with absolute URL too and same on trunk):

1. If the relative URL has fetchpriority='high' in the URL <img src="/wp-content/rocket-test-data/images/fetchpriority='high'.jpg">
2. If src was capital or has 1st letter capital or has space after it (If instead of src="imageURL" , SRC or Src or src = "imageURL")
3. If a commented exact markup was 1st on page, fetchpriority will be added to the commented markup instead of active one

<!-- <img src="/wp-content/rocket-test-data/images/lcp/testavif.avif"> -->

		<img src="/wp-content/rocket-test-data/images/lcp/testavif.avif">

4. LCP Image with Fetchpriority in markup, will have fetchpriority='high' and that will cause markup error. Example <img src="https://new.rocketlabsqa.ovh/wp-content/rocket-test-data/images/lcp/testavif.avif" fetchpriority> => seems regression and not on trunk @Khadreal can you please check?

@piotrbak Do you think we need GH for any of those cases 1-3?

[piotrbak]

@Mai-Saad I think those are edge cases, we should be good here

[Mai-Saad]

Related test plan https://wpmediaqa.testrail.io/index.php?/runs/view/854&group_by=cases:section_id&group_order=asc

[Khadreal]

@Mai-Saad handle the regression and 1 and 2 edge cases. We keep looking on how to resolve the 3rd one. You can do another test when you have some time.

[Khadreal]

@Mai-Saad I have added a fix for scenario 3 when there's a commented exact markup.

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Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for 2b088a335a85cb013d8186d2fc7e36f28d152c29[^1]	:white_check_mark: 100.00% (target: 50.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (2b088a335a85cb013d8186d2fc7e36f28d152c29)	Report Missing	Report Missing	Report Missing
Head commit (a55ac728f4a1af282fcdfa72e6e294c5bffc85ad)	37182	14376	38.66%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#6626)	12	12	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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_{Codacy will stop sending the deprecated coverage status from June 5th, 2024. Learn more} [^1]: Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct.