#64083 Trim the 6.7 workflows

[johnbillion]

For the 6.7 branch:

• Deletes unnecessary workflows
• Trims the unit testing matrix to the highest and lowest supported version of each major PHP branch.

Trac ticket: https://core.trac.wordpress.org/ticket/64083

[github-actions]

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[github-actions]

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[desrosj]

Few small suggestions. But supportive of this idea.

[desrosj]

Suggested change

	db-version: [ '10.4', '10.6', '10.11', '11.2' ]
	db-version: [ '10.6', '10.11' ]

11.2 was a rolling innovation release that is no longer supported. Since those releases have a short life-cycle, I lean towards saying that innovation/rolling releases are not included in test strategies for any non-supported branch.

I've also removed 10.4 here. I've opened #10166 to remove this version from trunk because usage across all WordPress sites has dropped below 1%.

[desrosj]

Suggested change

	db-version: '10.11'

If there's agreement on the point about dropping innovation/rolling releases, these includes should be changed to the newest LTS version supported in that version.

[desrosj]

Suggested change

	db-version: '10.11'

Same as above.