chore: CI "no space left" fixes

[crepererum]

Tracking the disk usage of the target folder via du -s target:

                   baseline: 16_398_968
+ CARGO_PROFILE_DEV_DEBUG=1: 14_219_908
+       CARGO_INCREMENTAL=0: 11_653_156
+    fix guest bundle flags:  9_896_220
+ workspace-hack (rejected): 10_770_560

Note that CARGO_INCREMENTAL=0 is already implied by https://github.com/Swatinem/rust-cache by, but it's still nice to be explicit.