Backport of Small fixes on UX of Automated Root Rotation parameters into release/1.19.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #29685 to be assessed for backporting due to the inclusion of the label backport/1.19.x.

The below text is copied from the body of the original PR.

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Description

Small fixes around the usability of the new automated root rotation parameters added to select Secret and Auth engines for 1.19 Enterprise.

This PR:

• enables rotation_period and rotation_window to be duration strings instead of just integers to be consistent with static role mechanisms
• makes it easier to zero out rotation params while setting others in the same call (previously user would have to unset rotation_period — which would first de-register — and then set rotation_schedule in a follow up call to re-register)
• fixes a bug where if disable_automated_rotation was not passed in a request, it was treated as being set to false, which would cause a de-registration. Now it will only de-register if the param is explicitly set to false
• removes an extra nested AutomatedRotationParams struct in the DB Config read method
• 'mutually exclusive' and 'incompatible fields' errors are only dispatched if fields are non-zero (UI sets rotation_period and rotation_window to 0, which was causing unnecessary errors)

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Overview of commits

• e8c07ec

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CI Results:
All Go tests succeeded! ✅

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Build Results:
All builds succeeded! ✅