ci: add job to run e2e tests multiple times #3334

Job	Run time
Lint: API (php-cs-fixer)	33s
Lint: ClientPrint (ESLint)	16s
Lint: e2e (ESLint)	20s
Lint: Frontend (ESLint)	42s
Lint: Print (ESLint)	25s
Tests: API	2m 0s
Tests: Frontend	1m 59s
Tests: PDF	25s
Tests: Print	49s
Tests: End-to-end build / Tests: End-to-end (build job)	50s
Tests: End-to-end run / Tests: End-to-end (chrome)	1m 1s
Tests: End-to-end run / Tests: End-to-end (firefox)	57s
Tests: End-to-end run / Tests: End-to-end (edge)	1m 0s
Finish coveralls report	1s
Send out CI success event	1s
	11m 19s

Provide feedback