add gdb, strace to workbench Dockerfile #7107

Job	Run time
Fetch product daily/preview versions	6s
Connect - Daily	10m 18s
Base Image Previews	8m 6s
Connect Content Init - Daily	1m 26s
Package Manager - Daily	6m 24s
Package Manager - Preview	6m 52s
R Session Complete - Daily	11m 6s
R Session Complete - Preview	11m 12s
Workbench - Daily	12m 44s
Workbench - Preview	12m 37s
Workbench Session Init - Daily	3m 20s
	1h 24m 11s

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