test: migrate runtime pytest.skip() to typed skip_bug()

Migrate 2 runtime pytest.skip() calls referencing known bugs to use
the typed skip_bug() wrapper from test.pylib.skip_types:

- test/alternator/test_ttl.py: Streams on tablets (#23838)
- test/scylla_gdb/test_task_commands.py: coroutine task not found (#22501)

test/alternator/test_ttl.py

@@ -13,7 +13,7 @@ from decimal import Decimal
 import pytest
 from botocore.exceptions import ClientError
 
-from test.pylib.skip_types import skip_env
+from test.pylib.skip_types import skip_bug, skip_env
 from .util import new_test_table, random_string, full_query, unique_table_name, is_aws, client_no_transform, multiset, scylla_config_read
 
 # The following fixture is to ensure that Alternator TTL is being tested with both vnodes and tablets.
@@ -656,6 +656,12 @@ def test_ttl_expiration_lsi_key(dynamodb, waits_for_expiration):
 # content), and a special userIdentity flag saying that this is not a regular
 # REMOVE but an expiration. Reproduces issue #11523.
 def test_ttl_expiration_streams(dynamodb, dynamodbstreams, waits_for_expiration):
+    # Alternator Streams currently doesn't work with tablets, so until
+    # #23838 is solved, skip this test on tablets.
+    for tag in TAGS:
+        if tag['Key'] == 'system:initial_tablets' and tag['Value'].isdigit():
+            skip_bug("Streams test skipped on tablets due to #23838")
+
     # In my experiments, a 30-minute (1800 seconds) is the typical
     # expiration delay in this test. If the test doesn't finish within
     # max_duration, we report a failure.

test/scylla_gdb/test_task_commands.py

@@ -8,6 +8,7 @@ Each only checks that the command does not fail - but not what it does or return
 
 import pytest
 
+from test.pylib.skip_types import skip_bug
 from test.scylla_gdb.conftest import execute_gdb_command
 
 pytestmark = [
@@ -34,7 +35,7 @@ def test_coroutine_frame(gdb_cmd):
     )
     if "COROUTINE_NOT_FOUND" in result.stdout:
         # See https://github.com/scylladb/scylladb/issues/22501
-        pytest.skip("Failed to find coroutine task. Skipping test.")
+        skip_bug("Failed to find coroutine task. Skipping test. https://github.com/scylladb/scylladb/issues/22501")
     assert result.returncode == 0, (
         f"GDB command `coro_frame` failed. stdout: {result.stdout} stderr: {result.stderr}"
     )