Revert "[loki-canary] Support passing loki address as environment variable (#8024)"

[JordanRushing]

What this PR does / why we need it:
This PR reverts commit f9ed9cb which introduced breaking config changes for the Loki canary. The relevant change introduced support for configuring a new LOKI_ADDRESS canary environment variable by adopting a new library for flags.

This is the easiest path forward to avoid forcing breaking config changes on canary operators; such a change is likely better suited to join other configuration changes in a future major Loki release.

Which issue(s) this PR fixes:
N/A

Special notes for your reviewer:
Related PR:

• [loki-canary] Support passing loki address as environment variable #8024

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• CHANGELOG.md updated
• Changes that require user attention or interaction to upgrade are documented in docs/sources/upgrading/_index.md

[grafanabot]

./tools/diff_coverage.sh ../loki-target-branch/test_results.txt test_results.txt ingester,distributor,querier,querier/queryrange,iter,storage,chunkenc,logql,loki

Change in test coverage per package. Green indicates 0 or positive change, red indicates that test coverage for a package fell.

+           ingester	0%
+        distributor	0%
+            querier	0%
+ querier/queryrange	0%
+               iter	0%
+            storage	0%
+           chunkenc	0%
+              logql	0%
+               loki	0%

[grafanabot]

./tools/diff_coverage.sh ../loki-target-branch/test_results.txt test_results.txt ingester,distributor,querier,querier/queryrange,iter,storage,chunkenc,logql,loki

Change in test coverage per package. Green indicates 0 or positive change, red indicates that test coverage for a package fell.

+           ingester	0%
+        distributor	0%
+            querier	0%
+ querier/queryrange	0%
+               iter	0%
+            storage	0%
+           chunkenc	0%
+              logql	0%
+               loki	0%

[slim-bean]

LGTM

[slim-bean]

@jijotj sorry to have revert this 😬 but unfortunately for all of us the Go stdlib flag parser allows for single dash var names even against long variables.

kingpin will fail to parse all of these as it expects a single dash to be a short name for a config.

Unfortunately this means basically everyones canary install is broken by this change 😞

I think if we were to make a change as big as this we'd want to tie it to a major release.

Since your original PR you were only looking to configure a few vars from the environment, I wonder if a smaller PR to just set those manually could be a compromise here?

[jijotj]

Oh cool, I chose kingpin because it was already used in the Loki ecosystem by logcli. Thanks for suggesting a compromise, I'll raise a PR to do just that.