[autobackport: sssd-2-10] tests: remove legacy intg test suite

[sssd-bot]

This is an automatic backport of PR#9078 tests: remove legacy intg test suite to branch sssd-2-10, created by @danlavu.

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Original commits
cbdb054 - tests: remove legacy intg test suite
5ce9d9e - CI: trim unused deps.sh/distro.sh helpers, rename matrix key, fix keytab leak
056c2e7 - CI: drop Debian as a build target

Backported commits

• 3061a68 - tests: remove legacy intg test suite
• 3b8dd8d - CI: trim unused deps.sh/distro.sh helpers, rename matrix key, fix keytab leak

Intentionally not backported

• 056c2e7 - CI: drop Debian as a build target — this commit re-points the
  codeql job at the ci-client-devel container make-distcheck
  already builds in, which has a newer OpenSSL where ASN1_STRING is
  opaque and i2d_ASN1_TYPE is no longer usable the way this branch's
  src/lib/certmap/sss_cert_content_crypto.c expects — codeql
  currently passes on this branch unmodified, and backporting this
  commit broke it. A full fix requires a much larger, deliberate "Drop
  support of OpenSSL < 3.0.8" effort (master PR Drop support of OpenSSL < 3.0.8 #8761) not yet applied
  here, so this commit's scope reduction (Debian/Ubuntu removal from
  CI) is left out of this backport rather than regress codeql.

Conflict resolution notes

Both backported commits conflicted on this branch; no semantic change
vs. upstream, only adjustments for structural gaps that predate this
PR:

• build.yml: this branch doesn't have -Werror yet, so kept the
  make/make check invocations without it, just adding -g3 and
  the new check-valgrind step.
• Makefile.am: script/data lists conflicted because this branch
  hasn't absorbed a later, unrelated master-only reorg that moved
  configure.sh/deps.sh/distro.sh/get-matrix.py into
  dist_noinst_SCRIPTS; kept this branch's existing layout and
  applied only this PR's actual deletions/additions. Also dropped the
  entire intgcheck-prepare/-run/-clean target block.
• get-matrix.py: this branch has no usable fedora variable in
  scope at the matrix-dict callsite, so the multihost/system
  matrix stays centos-only.
• pamsrv.c: this branch has the dead #ifndef INTGCHECK_BUILD
  guard but never picked up the later LISTEN_PID/LISTEN_FDS
  socket-activation block, so just dropped the guard around the
  existing clearenv() code.
• .github/workflows/coverity.yml was already deleted independently
  on this branch (CI: disable coverity in maintenance branches) —
  kept it deleted.

One post-push make-distcheck compile failure found and fixed: the
auto-merge of commit 2 carried over master's
unlink(IPA_ONEWAY_TWO_KEYTAB); keytab cleanup into
test_ipa_subdomains_server.c's test_ipa_server_create_trusts_twoway(),
but this branch's version of that test uses a single, simpler
ONEWAY_KEYTAB macro (no IPA_ONEWAY_TWO_KEYTAB) and already unlinks
it in the shared teardown — so the line didn't apply and failed to
compile. Removed it; no real leak existed on this branch. This also
fixed the downstream rpm-build/system (centos-10)/testing-farm
failures, which were all consequences of the same compile error.

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Original Pull Request Body

Remove the legacy Python/pytest-based intg test suite under
src/tests/intg along with its supporting build glue
(intgcheck.m4, contrib/ci --moderate scope, screenrc/cwrap config,
etc.). Coverage has moved to the system test suite
(src/tests/system) and to the make check test suite run under
Valgrind in GitHub Actions.

• Keep the make check-valgrind check in the distcheck job
  (.github/workflows/build.yml), since it previously ran via the
  intgcheck job's contrib/ci/run --moderate invocation.
• Remove the now-dead INTGCHECK_BUILD guard in
  src/responder/pam/pamsrv.c; the macro is no longer defined
  anywhere, so the guarded code (clearing dangerous env vars like
  LDB_MODULES_PATH) always runs now.
• Drop the now-unused --essential/--moderate option from
  contrib/ci/run (the MODERATE variable was set but never read once
  the intg-backed moderate scope was removed) and update
  contrib/ci/README.md to match.
• Build make/make check/distcheck with -g3, matching the debug info
  level contrib/ci/run previously used for its Valgrind build, for
  better Valgrind/backtrace output.

AI: Claude Sonnet 5
Co-authored-by: Cursor cursoragent@cursor.com