Optimize disk space usage in CI by pruning all unused Docker images (… #14

Job	Run time
Check whether tests need to be run based on diff	22s
Verify docs and spelling	53s
Integration test	10m 31s
Unit test (ubuntu-latest)	6m 47s
Golangci-lint (macos-latest)	7m 22s
Golangci-lint (ubuntu-latest)	8m 14s
Unit test (windows-2022)	12m 10s
Build Antrea and antctl binaries	10m 12s
Go benchmark test	4m 46s
Build Antrea Windows binaries	1m 58s
Check tidy, code generation and manifest	5m 17s
	1h 8m 32s

Provide feedback