fix(conformance): chainsaw checks use contains(), not unsupported =~

Every chainsaw `check` used the regex operator `=~` (`($stdout =~ 'X'): true`),
which chainsaw's expression engine rejects ('SyntaxError: Unknown char: ~') — so
EVERY such test failed on the assertion even when the behavior passed. Proven with
data-survival (R-STATE-01): the Longhorn canary genuinely SURVIVED pod destruction
(DATA_SURVIVED_OK) but the test FAILED on the `=~` syntax. Converted all 10 tests to
JMESPath `contains($stdout, 'X')` (data-survival's alternation → contains||contains).
data-survival now PASSES; the other 9 (later-phase components) are syntactically fixed
for when their phases deploy.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

conformance/tests/l3-fault-injection/gitops-drift/chainsaw-test.yaml

@@ -45,7 +45,7 @@ spec:
               set -euo pipefail
               echo "TODO: within Flux interval, assert live value == git-declared value"
               echo "DRIFT_REVERTED_OK"
-            check: { ($stdout =~ 'DRIFT_REVERTED_OK'): true }
+            check: { (contains($stdout, 'DRIFT_REVERTED_OK')): true }
       finally:
         - script:
             content: 'echo "TODO: ensure resource left in git-declared state"'