a3f61676e8 test: Make more shell scripts verifiable by the `shellcheck` tool (Hennadii Stepanov)
Pull request description:
Some shell scripts from `contrib/guix` and `contrib/shell` are not verifiable by the `shellcheck` tool for the following reasons:
- they have no extension (see 4eccf063b2 from bitcoin/bitcoin#21375)
- they have the `.bash` extension while `.sh` is expected
This PR adds these scripts to the input for the `shellcheck` tool, and it fixes discovered `shellcheck` warnings.
ACKs for top commit:
dongcarl:
Code Review ACK a3f61676e8, this is a good robustness improvement for our shell scripts.
jamesob:
crACK a3f61676e8
Tree-SHA512: 6703f5369d9c04c1a174491f381afa5ec2cc4d37321c1b93615abcdde4dfd3caae82868b699c25b72132d8c8c6f2e9cf24d38eb180ed4d0f0584d8c282e58935