Update deprecation message for google_project.skip_delete

[rileykarson]

Quick deprecation message update after #11359 as updating within 5.X is possible.

fyi @abd-goog @zli82016

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 2 files changed, 6 insertions(+), 3 deletions(-))
google-beta provider: Diff ( 2 files changed, 6 insertions(+), 3 deletions(-))

Missing test report

Your PR includes resource fields which are not covered by any test.

Resource: google_project (887 total tests)
Please add an acceptance test which includes these fields. The test should include the following:

resource "google_project" "primary" {
  skip_delete = # value needed
}

[modular-magician]

Tests analytics

Total tests: 144
Passed tests: 114
Skipped tests: 30
Affected tests: 0

Click here to see the affected service packages

• resourcemanager

$\textcolor{green}{\textsf{All tests passed!}}$

View the build log

[zli82016]

LGTM. Thanks for catching it.