fix[installer]: add -a flag to docker system prune to remove unused i… #600

Job	Run time
Setup Deployment	3s
Build Event Processor Microservice	6m 20s
Build Agent Binaries	4m 26s
Build UTMStack Collector	1m 19s
Build Frontend Microservice / build	4m 29s
Build User-Auditor Microservice / Build & Push Java 11 Image	1m 35s
Build Backend Microservice / Build & Push Java 17 Image	2m 44s
Build Web-PDF Microservice / Build & Push Java 11 Image	1m 40s
Promote to Community	-1s
Sign macOS Agent Binaries / Sign macos binaries	1m 11s
Sign Windows Agent Binaries / Sign windows binaries	47s
Build Agent Manager Microservice	1m 52s
All Builds Complete	4s
Deploy Installer (Dev) / Deploy V11 to Dev Runner	7s
Publish New Version to Customer Manager	9s
Generate Changelog	0s
Deploy Installer (Dev) / Build V11 Installer for Release	0s
Deploy Installer (Dev) / Upload V10 Installer to Prerelease	0s
Deploy Installer (Dev) / Deploy V10 to RC Runner	0s
Deploy Installer (Dev) / Deploy V10 to Dev Runner	0s
Build & Upload Installer	-1s
Schedule release to our instances	3s
	26m 47s

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