Updated usage of " eq " in instance template filters

[modular-magician]

Resolved #8936

When the google compute instance template API was first introduced, it allowed filtering based on the eq keyword; however, that has not been a documented keyword for ~3 years, and seems to no longer work. Additionally, the new filters don't support regular expressions.

UPDATE: It looks like I was incorrect about the root cause. Here's an example failure: https://ci-oss.hashicorp.engineering/repository/download/GoogleCloudBeta_ProviderGoogleCloudBetaGoogleProject/183032:id/debug-google-beta-309e845-TestAccInstanceTemplateDatasource_filter.log The failure was not due to all three templates (a, b, c) being available, but rather due to there actually being 3 instances that matched, presumably due to concurrent test runs.

That being said, I still believe we should make this update, since it brings us in line with the currently-documented behavior. Also, by ensuring that the most recent instance template with / without filtering are different, we can make sure that if filtering does break in the future, we will catch it.

Test run demonstrating failures after first commit: https://ci-oss.hashicorp.engineering/buildConfiguration/GoogleCloudBeta_ProviderGoogleCloudBetaMmUpstream/183267

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Derived from GoogleCloudPlatform/magic-modules#4719

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