MGetCachingModeBug2276 unit test failed randomly

[kostasrim]

https://github.com/dragonflydb/dragonfly/actions/runs/8643026242/job/23695199095#step:10:2777

Triggered the assertion:

58: [ RUN      ] StringFamilyTest.MGetCachingModeBug2276
58: I20240411 07:30:21.029148 24335 proactor_pool.cc:146] Running 3 io threads
58: I20240411 07:30:21.029711 24335 test_utils.cc:218] Starting MGetCachingModeBug2276
58: I20240411 07:30:21.040745 24335 proactor_pool.cc:146] Running 3 io threads
58: I20240411 07:30:21.041234 24335 test_utils.cc:218] Starting MGetCachingModeBug2276
58: ../src/server/string_family_test.cc:272: Failure
58: Expected: (bumps1) > (0), actual: 0 vs 0
58: [_deps/abseil_cpp-src/absl/flags/internal/flag.cc : 113] RAW: Restore saved value of cache_mode to: false
58: [_deps/abseil_cpp-src/absl/flags/internal/flag.cc : 113] RAW: Restore saved value of dbfilename to: 
58: I20240411 07:30:21.065528 24335 test_utils.cc:178] Finishing MGetCachingModeBug2276
58: [  FAILED  ] StringFamilyTest.MGetCachingModeBug2276 (36 ms)
58: [ RUN      ] StringFamilyTest.MGetCachingModeBug2465