Compactor OOM in nightly-20240512 longevity test

[huangjw806]

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longevity-test Result
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Result               FAIL                
Pipeline Message     run all nexmark (8 sets of nexmark queries) with 10k throughput daily
Namespace            reglngvty-20240512-150222
TestBed              medium-arm-3cn-all-affinity
RW Version           nightly-20240512    
Test Start time      2024-05-12 15:11:54 
Test End time        2024-05-13 03:14:11 
Test Queries         nexmark_q0,nexmark_q1,nexmark_q2,nexmark_q3,nexmark_q4,nexmark_q5,nexmark_q6_group_top1,nexmark_q7,nexmark_q8,nexmark_q9,nexmark_q10,nexmark_q12,nexmark_q14,nexmark_q15,nexmark_q16,nexmark_q17,nexmark_q18,nexmark_q19,nexmark_q20,nexmark_q21,nexmark_q22,nexmark_q101,nexmark_q102,nexmark_q103,nexmark_q104,nexmark_q105
Grafana Metric       https://grafana.test.risingwave-cloud.xyz/d/EpkBw5W4k/risingwave-dev-dashboard?orgId=1&var-datasource=Prometheus:%20test-useast1-eks-a&var-namespace=reglngvty-20240512-150222&from=1715526714000&to=1715570051000
Grafana Logs         https://grafana.test.risingwave-cloud.xyz/d/liz0yRCZz1/log-search-dashboard?orgId=1&var-data_source=Logging:%20test-useast1-eks-a&var-namespace=reglngvty-20240512-150222&from=1715526714000&to=1715570051000
Memory Dumps         https://s3.console.aws.amazon.com/s3/buckets/test-useast1-mgmt-bucket-archiver?region=us-east-1&bucketType=general&prefix=k8s/reglngvty-20240512-150222/&showversions=false
Buildkite Job        https://buildkite.com/risingwave-test/longevity-test/builds/1378

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Restarted/Crashed Pods Details
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Pod crashed/Restarted: benchmark-risingwave-compactor-c-69f948565f-bz2tt restart_count:24  phase:Running status:True

[Li0k]

fix by #16727

The meta cache lacks a weighter pass to calculate entry memory usage, causing the meta cache to actually use more memory than the limit, which triggers an oom.