fix: ignore tags passed on startup

[michaelhtm]

Issue #2673

Description of changes:
With this change, ACK now ignores tags that are passed on startup.
On top of that it also valdidates ResourceTags on startup, instead of
doing so during reconcile.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[a-hilaly]

👍

[ack-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: a-hilaly, michaelhtm

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[ack-prow]

@michaelhtm: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
unit-test	5ac3dfa	link	true	/test unit-test
verify-attribution	a196b41	link	false	/test verify-attribution
ecr-controller-test	a196b41	link	true	/test ecr-controller-test
iam-controller-test	a196b41	link	true	/test iam-controller-test
sagemaker-controller-test	a196b41	link	true	/test sagemaker-controller-test
s3-controller-test	a196b41	link	true	/test s3-controller-test
sqs-controller-test	a196b41	link	true	/test sqs-controller-test
ec2-controller-test	a196b41	link	true	/test ec2-controller-test

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