Please backport subset of 2f5d370dec3f ("perf test: Change all remaining #!/bin/sh to #!/bin/bash") for stat_bpf_counters.sh script to v6.12.y and older

[Salvatore Bonaccorso]

Hi

Recently for v5.15.221, v6.1.188, v6.6.157, v6.12.110, v6.18.52 and
v7.2.6, the commit b02027776ac5 ("perf tests: Fix flakiness in BPF
counters test on hybrid systems") was backported, but it introduced
bash specific syntax.  For versions after 2f5d370dec3f ("perf test:
Change all remaining #!/bin/sh to #!/bin/bash") aka before v6.17-rc1
this is not a problem.

The proposed patch is a stable series backports specific one, as one
cannot simply backport 2f5d370dec3f ("perf test: Change all remaining
#!/bin/sh to #!/bin/bash") without picking as well some other context
related changes to make it possible. So I was proposing to only change
shebang to #!/bin/bash in stable series were it is a problem, as in
the stat_bpf_counters.sh script.

Regards,
Salvatore