TestBatchSplitRegionByRangesScanFailed tasks too many time

[hawkingrei]

Bug Report

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1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

3. What did you see instead (Required)

takes 256.34s. It is too long.

[2023/02/16 13:30:46.210 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:47.211 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:48.212 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:49.213 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:50.214 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:51.215 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:52.216 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:53.216 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
[2023/02/16 13:30:54.217 +08:00] [WARN] [split.go:115] ["failed to scan region, retrying"] [error="scan region return empty result, startKey: 6200000000000000F8, endKey: 627A000000000000F9: [BR:PD:ErrPDBatchScanRegion]batch scan region"]
--- PASS: TestBatchSplitRegionByRangesScanFailed (256.34s)

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