[MAIN] Remove "DELETE" from the Serving validating webhook

[skonto]

What this PR does / why we need it:

• Similar to [RELEASE-1.15] Remove "DELETE" from the Serving validating webhook #1103
• Related also to SRVKS-1301 and RHOAIENG-18590

Which issue(s) this PR fixes:

JIRA:

Does this PR needs for other branches:

Does this PR (patch) needs to update/drop in the future?:

JIRA:

[dsimansk]

/approve
/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dsimansk, skonto

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[openshift-cherrypick-robot]

@skonto: cannot checkout release-vX.Y: error checking out "release-vX.Y": exit status 1 error: pathspec 'release-vX.Y' did not match any file(s) known to git

In response to this:

What this PR does / why we need it:

• Similar to [RELEASE-1.15] Remove "DELETE" from the Serving validating webhook #1103
• Related also to SRVKS-1301 and RHOAIENG-18590

Which issue(s) this PR fixes:

JIRA:

Does this PR needs for other branches:

Does this PR (patch) needs to update/drop in the future?:

JIRA:

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