Support event trigger for Neon users

[knizhnik]

Problem

#7570

Even triggers are supported only for superusers.

Summary of changes

Temporary switch to superuser when even trigger is created and disable execution of user's even triggers under superuser.

[github-actions]

7414 tests run: 7036 passed, 26 failed, 352 skipped (full report)

---

Failures on Postgres 17

• test_pg_regress[None]: release-x86-64-with-lfc, release-x86-64-without-lfc, release-arm64-without-lfc, release-arm64-with-lfc, debug-x86-64-without-lfc
• test_pg_regress[4]: release-x86-64-without-lfc, release-x86-64-with-lfc, release-arm64-with-lfc, debug-x86-64-without-lfc, release-arm64-without-lfc

Failures on Postgres 16

• test_pg_regress[None]: release-x86-64-with-lfc, release-arm64-with-lfc
• test_pg_regress[4]: release-x86-64-with-lfc, release-arm64-with-lfc
• test_postgres_version: release-x86-64-with-lfc, release-arm64-with-lfc

Failures on Postgres 15

• test_pg_regress[4]: release-x86-64-with-lfc, release-arm64-with-lfc
• test_pg_regress[None]: release-x86-64-with-lfc, release-arm64-with-lfc
• test_postgres_version: release-x86-64-with-lfc, release-arm64-with-lfc

Failures on Postgres 14

• test_pg_regress[4]: release-x86-64-with-lfc, release-arm64-with-lfc
• test_pg_regress[None]: release-x86-64-with-lfc, release-arm64-with-lfc

# Run all failed tests locally:
scripts/pytest -vv -n $(nproc) -k "test_pg_regress[release-pg14-4] or test_pg_regress[release-pg14-4] or test_pg_regress[release-pg14-None] or test_pg_regress[release-pg14-None] or test_pg_regress[release-pg15-4] or test_pg_regress[release-pg15-4] or test_pg_regress[release-pg15-None] or test_pg_regress[release-pg15-None] or test_postgres_version[release-pg15] or test_postgres_version[release-pg15] or test_pg_regress[release-pg16-None] or test_pg_regress[release-pg16-None] or test_pg_regress[release-pg16-4] or test_pg_regress[release-pg16-4] or test_postgres_version[release-pg16] or test_postgres_version[release-pg16] or test_pg_regress[release-pg17-None] or test_pg_regress[release-pg17-None] or test_pg_regress[release-pg17-None] or test_pg_regress[release-pg17-None] or test_pg_regress[debug-pg17-None] or test_pg_regress[release-pg17-4] or test_pg_regress[release-pg17-4] or test_pg_regress[release-pg17-4] or test_pg_regress[debug-pg17-4] or test_pg_regress[release-pg17-4]"

Test coverage report is not available

_{The comment gets automatically updated with the latest test results
9783475 at 2025-02-02T08:24:30.550Z :recycle:}