chore: retry flares cleanup on tests to remove flakiness on CI (#15198)

## Description

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## Testing

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## Risks

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## Additional Notes

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Signed-off-by: Juanjo Alvarez <juanjo.alvarezmartinez@datadoghq.com>

Author: juanjux

tests/internal/test_tracer_flare.py

@@ -23,6 +23,7 @@
 from ddtrace.internal.flare.handler import _handle_tracer_flare
 from ddtrace.internal.logger import get_logger
 from ddtrace.internal.remoteconfig._connectors import PublisherSubscriberConnector
+from ddtrace.internal.utils.retry import fibonacci_backoff_with_jitter
 from tests.utils import remote_config_build_payload as build_payload
 
 
@@ -214,6 +215,7 @@ def test_json_logs(self):
         self.flare.clean_up_files()
         self.flare.revert_configs()
 
+    @fibonacci_backoff_with_jitter(attempts=5, initial_wait=0.1)
     def confirm_cleanup(self):
         assert not self.flare.flare_dir.exists(), f"The directory {self.flare.flare_dir} still exists"
         # Only check for file handler cleanup if prepare() was called