Grafana install fails with default config due to GPG key rotation

[Samuel Allan]

The gpg signing key for grafana was recent rotated: https://grafana.com/blog/2023/08/24/grafana-security-update-gpg-signing-key-rotation/

This causes installation to fail with the default config now.

A workaround:

```
$ juju config grafana install_keys="- |
    -----BEGIN PGP PUBLIC KEY BLOCK-----

    mQGNBGTnhmkBDADUE+SzjRRyitIm1siGxiHlIlnn6KO4C4GfEuV+PNzqxvwYO+1r
    mcKlGDU0ugo8ohXruAOC77Kwc4keVGNU89BeHvrYbIftz/yxEneuPsCbGnbDMIyC
    k44UOetRtV9/59Gj5YjNqnsZCr+e5D/JfrHUJTTwKLv88A9eHKxskrlZr7Un7j3i
    Ef3NChlOh2Zk9Wfk8IhAqMMTferU4iTIhQk+5fanShtXIuzBaxU3lkzFSG7VuAH4
    CBLPWitKRMn5oqXUE0FZbRYL/6Qz0Gt6YCJsZbaQ3Am7FCwWCp9+ZHbR9yU+bkK0
    Dts4PNx4Wr9CktHIvbypT4Lk2oJEPWjcCJQHqpPQZXbnclXRlK5Ea0NVpaQdGK+v
    JS4HGxFFjSkvTKAZYgwOk93qlpFeDML3TuSgWxuw4NIDitvewudnaWzfl9tDIoVS
    Bb16nwJ8bMDzovC/RBE14rRKYtMLmBsRzGYHWd0NnX+FitAS9uURHuFxghv9GFPh
    eTaXvc4glM94HBUAEQEAAbQmR3JhZmFuYSBMYWJzIDxlbmdpbmVlcmluZ0BncmFm
    YW5hLmNvbT6JAdQEEwEKAD4WIQS1Oud7rbYwpoMEYAWWP6J3EEWFRQUCZOeGaQIb
    AwUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRCWP6J3EEWFRUiADACa
    i+xytv2keEFJWjXNnFAx6/obnHRcXOI3w6nH/zL8gNI7YN5jcdQT2NYvKVYTb3fW
    GuMsjHWgat5Gq3AtJrOKABpZ6qeYNPk0Axn/dKtOTwXjZ4pKX3bbUYvVfs0fCEZv
    B0HHIj2wI9kgMpoTrkj22LE8layZTPOoQ+3/FbLzS8hN3CYZj25mHN7bpZq8EbV3
    8FW9EU0HM0tg6CvoxkRiVqAuAC0KnVIZAdhD4dlYKuncq64nMvT1A5wxSYbnE+uf
    mnWQQhhS6BOwRqN054yw1FrWNDFsvnOSHmr8dIiriv+aZYvx5JQFJ7oZP3LwdYyg
    ocQcAJA8HFTIk3P6uJiIF/zdDzocgdKs+IYDoId0hxX7sGCvqdrsveq8n3m7uQiN
    7FvSiV0eXIdV4F7340kc8EKiYwpuYSaZX0UWKLenzlUvD+W4pZCWtoXzPsW7PKUt
    q1xdW0+NY+AGLCvSJCc5F4S5kFCObfBAYBbldjwwJFocdq/YOvvWYTPyV7kJeJS5
    AY0EZOeGaQEMALNIFUricEIwtZiX7vSDjwxobbqPKqzdek8x3ud0CyYlrbGHy0k+
    FDEXstjJQQ1s9rjJSu3sv5wyg9GDAUH3nzO976n/ZZvKPti3p2XU2UFx5gYkaaFV
    D56yYxqGY0YU5ft6BG+RUz3iEPg3UBUzt0sCIYnG9+CsDqGOnRYIIa46fu2/H9Vu
    8JvvSq9xbsK9CfoQDkIcoQOixPuI4P7eHtswCeYR/1LUTWEnYQWsBCf57cEpzR6t
    7mlQnzQo9z4i/kp4S0ybDB77wnn+isMADOS+/VpXO+M7Zj5tpfJ6PkKch3SGXdUy
    3zht8luFOYpJr2lVzp7n3NwB4zW08RptTzTgFAaW/NH2JjYI+rDvQm4jNs08Dtsp
    nm4OQvBA9Df/6qwMEOZ9i10ixqk+55UpQFJ3nf4uKlSUM7bKXXVcD/odq804Y/K4
    y3csE059YVIyaPexEvYSYlHE2odJWRg2Q1VehmrOSC8Qps3xpU7dTHXD74ZpaYbr
    haViRS5v/lCsiwARAQABiQG8BBgBCgAmFiEEtTrne622MKaDBGAFlj+idxBFhUUF
    AmTnhmkCGwwFCQPCZwAACgkQlj+idxBFhUUNbQv8DCcfi3GbWfvp9pfY0EJuoFJX
    LNgci7z7smXq7aqDp2huYQ+MulnPAydjRCVW2fkHItF2Ks6l+2/8t5Xz0eesGxST
    xTyR31ARENMXaq78Lq+itZ+usOSDNuwJcEmJM6CceNMLs4uFkX2GRYhchkry7P0C
    lkLxUTiB43ooi+CqILtlNxH7kM1O4Ncs6UGZMXf2IiG9s3JDCsYVPkC5QDMOPkTy
    2ZriF56uPerlJveF0dC61RZ6RlM3iSJ9Fwvea0Oy4rwkCcs5SHuwoDTFyxiyz0QC
    9iqi3fG3iSbLvY9UtJ6X+BtDqdXLAT9Pq527mukPP3LwpEqFVyNQKnGLdLOu2YXc
    TWWWseSQkHRzBmjD18KTD74mg4aXxEabyT4snrXpi5+UGLT4KXGV5syQO6Lc0OGw
    9O/0qAIU+YW7ojbKv8fr+NB31TGhGYWASjYlN1NvPotRAK6339O0/Rqr9xGgy3AY
    SR+ic2Y610IM7xccKuTVAW9UofKQwJZChqae9VVZ
    =J9CI
    -----END PGP PUBLIC KEY BLOCK-----
"
$ juju config grafana install_sources='deb https://apt.grafana.com stable main'
```

[Mert Kirpici (mertkirpici)]

Hi there Samuel, I did supersede your MP with the additional commit that fixes the build problem. I cherry-picked your commit to keep all your work intact. It was necessary since neither of the two fixes can produce a green CI job alone. There are intermittent issues with the CI, which should hopefully be resolved today and this will get merged.

Thanks for the patch.

[Samuel Allan (samuelallan)]

Awesome, yes I saw you fixed the CI, thank you! :) I tried to reassign the launchpad bug to you, but it wasn't finding you - maybe permissions issues.

[Mert Kirpici (mertkirpici)]

The revision that includes the fix is now released to the edge channel.