The `-j` switch passed to `tar` indicates the archive is compressed using the
bzip2 format (`bz2` extension). That was how Firefox used to be compressed until
recently, but the new ESR release now uses xz. Ubuntu `tar` doesn't auto-guess
the encryption algorithm, so to support both, first try with xz and fall back
to bzip2 if that fails.

Note: this will download the old Firefox ESR twice, but it will still work
when the current ESR version starts to use xz with no changes to the code

Ref jquerygh-5682

The `-j` switch passed to `tar` indicates the archive is compressed using the
bzip2 format (`bz2` extension). That was how Firefox used to be compressed until
recently, but the new ESR release now uses xz. Ubuntu `tar` doesn't auto-guess
the encryption algorithm, so to support both, first try with xz and fall back
to bzip2 if that fails.

Note: this will download the old Firefox ESR twice, but it will still work
when the current ESR version starts to use xz with no changes to the code.

Ref jquerygh-5682

The `-j` switch passed to `tar` indicates the archive is compressed using the
bzip2 format (`bz2` extension). That was how Firefox used to be compressed until
recently, but the new ESR release now uses xz. Ubuntu `tar` doesn't auto-guess
the encryption algorithm, so to support both, first try with xz and fall back
to bzip2 if that fails.

Note: this will download the old Firefox ESR twice, but it will still work
when the current ESR version starts to use xz with no changes to the code.

Closes gh-5684
Ref gh-5682

The previous config declared Firefox ESR testing, but the tests were never run
due to clashing names with main Firefox test runs. Apart from fixing that,
backport jquery/jquery#5682 so that both Firefox ESR versions can be downloaded
despite using different compression algorithms.

Ref jquery/jquery#5682

The previous config declared Firefox ESR testing, but the tests were never run
due to clashing names with main Firefox test runs. Apart from fixing that,
backport jquery/jquery#5682 so that both Firefox ESR versions can be downloaded
despite using different compression algorithms.

Ref jquery/jquery#5682

The previous config declared Firefox ESR testing, but the tests were never run
due to clashing names with main Firefox test runs. Apart from fixing that,
backport jquery/jquery#5682 so that both Firefox ESR versions can be downloaded
despite using different compression algorithms.

Ref jquery/jquery#5682

The previous config declared Firefox ESR testing, but the tests were never run
due to clashing names with main Firefox test runs. Apart from fixing that,
backport jquery/jquery#5682 so that both Firefox ESR versions can be downloaded
despite using different compression algorithms.

Ref jquerygh-597
Ref jquery/jquery#5682

The previous config declared Firefox ESR testing, but the tests were never run
due to clashing names with main Firefox test runs. Apart from fixing that,
backport jquery/jquery#5682 so that both Firefox ESR versions can be downloaded
despite using different compression algorithms.

Ref jquerygh-598
Ref jquery/jquery#5682

The previous config declared Firefox ESR testing, but the tests were never
run due to clashing names with main Firefox test runs. Apart from fixing
that, backport jquery/jquery#5682 so that both Firefox ESR versions can be
downloaded despite using different compression algorithms.

Also, Simplify caching in CI: our setup is pretty standard, so manual
configuration of `actions/cache` is an overkill. Relying on built-in
`actions/node` caching will also resolve differences between caching
configurations for macOS/Linux vs. Windows.

Closes gh-597
Ref gh-598
Ref jquery/jquery#5682

The previous config declared Firefox ESR testing, but the tests were never
run due to clashing names with main Firefox test runs. Apart from fixing
that, backport jquery/jquery#5682 so that both Firefox ESR versions can be
downloaded despite using different compression algorithms.

Also, Simplify caching in CI: our setup is pretty standard, so manual
configuration of `actions/cache` is an overkill. Relying on built-in
`actions/node` caching will also resolve differences between caching
configurations for macOS/Linux vs. Windows.

Closes gh-598
Ref gh-597
Ref jquery/jquery#5682