Boost: add cache rebuild functionality #78833

Job	Run time
Determine tests matrix	1m 7s
E2E: Build jetpack-boost	3m 9s
Jetpack Boost - Base e2e tests	2m 45s
Jetpack Boost - Modules e2e tests	3m 52s
Jetpack Boost - Critical CSS e2e tests	3m 32s
Jetpack Boost - Page Cache e2e tests	6m 29s
Jetpack Boost - Concatenate JS/CSS e2e tests	3m 31s
Jetpack Boost - Image CDN e2e tests	3m 48s
Jetpack Boost - Image Guide e2e tests	2m 43s
Slack notification	1m 0s
Test report	4s
	32m 0s

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