fix: pull changes from managed schemas separately

[sweatybridge]

What kind of change does this PR introduce?

Bug fix#4068

What is the new behavior?

Using the pgkit/migra implementation, we can reliably pull triggers and policies from managed schemas.

Hence, we can start doing that automatically instead of printing a suggestion.

For user defined schemas, use original migra to avoid revoking permissions.

Additional context

Add any other context or screenshots.

[coveralls]

Pull Request Test Coverage Report for Build 17692370276

Details

• 18 of 63(28.57%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.2%) to 54.792%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/db/pull/pull.go	18	63	28.57%

Files with Coverage Reduction	New Missed Lines	%
internal/db/pull/pull.go	1	59.52%
internal/gen/keys/keys.go	5	12.9%

Totals
Change from base Build 17678821493:	-0.2%
Covered Lines:	6260
Relevant Lines:	11425

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💛 - Coveralls