Ignore submodule qa-test-data

this would currently break the mypy aspect:
```
make -C tests test-mypy
make: Entering directory '/home/foo/git/check_mk/master/tests'
bazel build --config=mypy ...
INFO: Invocation ID: 20306022-0856-4c05-8fae-3017e643357c
WARNING: Target pattern parsing failed.
ERROR: Skipping '...': error loading package under directory 'tests': error loading package 'tests/qa-test-data': Unable to find package for @@[unknown repo 'pypi' requested from @@]//:requirements.bzl: The repository '@@[unknown repo 'pypi' requested from @@]' could not be resolved: No repository visible as '@pypi' from main repository.
ERROR: error loading package under directory 'tests': error loading package 'tests/qa-test-data': Unable to find package for @@[unknown repo 'pypi' requested from @@]//:requirements.bzl: The repository '@@[unknown repo 'pypi' requested from @@]' could not be resolved: No repository visible as '@pypi' from main repository.
INFO: Elapsed time: 0.208s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
make: *** [Makefile:337: test-mypy-cmk] Error 1
make: Leaving directory '/home/foo/git/check_mk/master/tests'
```

see also https://tribe29.slack.com/archives/CGBE6U2PK/p1769755982549569

Change-Id: I7ce9fee5a3827d8cd4b08942b3ec3182b9630379

Author: TimotheusBachinger

.bazelignore

@@ -8,3 +8,5 @@ packages/cmk-frontend/node_modules
 packages/cmk-frontend-vue/node_modules
 packages/cmk-shared-typing/node_modules
 packages/cmk-werks/node_modules
+
+tests/qa-test-data