Use backoff in time machine test to reduce flakiness (hopefully) #4682

Job	Run time
package_builder (ubuntu-20.04)	52s
launcher (ubuntu-20.04)	3m 56s
package_builder (macos-12)	1m 44s
launcher (macos-12)	10m 0s
package_builder (windows-latest)	4m 35s
launcher (windows-latest)	10m 11s
Version Baseline	2s
Exec Test (ubuntu-20.04)	8s
Exec Test (ubuntu-22.04)	4s
Exec Test (macos-11)	20s
Exec Test (macos-12)	19s
Exec Test (macos-13)	24s
Exec Test (windows-2019)	19s
Exec Test (windows-2022)	20s
Store Artifacts (linux)	14s
Store Artifacts (macos)	32s
ci_mergeable	1s
Store Artifacts (windows)	14s
	34m 15s

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