Fix bug hidden on CI and make ci failed if tests failure (#29254) (#29662)

Fix bug hidden on CI and make ci failed if tests failure (#29254) (#29662)

Backport #29254

The tests on migration tests failed but CI reports successfully

https://github.com/go-gitea/gitea/actions/runs/7364373807/job/20044685969#step:8:141

This PR will fix the bug on migrations and also the CI hidden behaviour.

The reason is on the Makefile

`GITEA_ROOT="$(CURDIR)" GITEA_CONF=tests/mysql.ini $(GO) test
$(GOTESTFLAGS) -tags='$(TEST_TAGS)' $(MIGRATE_TEST_PACKAGES)` will
return the error exit code.

But

`for pkg in $(shell $(GO) list
code.gitea.io/gitea/models/migrations/...); do \
GITEA_ROOT="$(CURDIR)" GITEA_CONF=tests/mysql.ini $(GO) test
$(GOTESTFLAGS) -tags '$(TEST_TAGS)' $$pkg; \
	done`

will not work.

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Co-authored-by: Giteabot <teabot@gitea.io>