CI: fix sccache timeout #6612

Job	Run time
Rust tests (miri)	1m 34s
Rust/C++ FFI tests (tsan)	1m 59s
C++ API (coverage)	1m 1s
Rust tests (tsan)	6m 38s
Rust tests (asan)	6m 55s
Rust/C++ FFI tests (asan)	2m 6s
Mirror DuckDB to R2 / Resolve DuckDB version and check R2	7s
Mirror DuckDB to R2 / Mirror DuckDB ${{ matrix.archive }} to R2	0s
DuckDB libraries available in R2	4s
Rust tests (coverage) (tests)	6m 31s
	26m 55s

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