Chore: a bit of spring cleaning (#16710)

* Chore: use early return technic everywhere

And enable "indent-error-flow" revive rule

* Chore: remove if-return rule from revive config

* Chore: improve error messages

And enable "error-strings" revive rule

* Chore: enable "error-naming" revive rule

* Chore: make linter happy

* Chore: do not duplicate gofmt execution

* Chore: make linter happy

* Chore: address the pull review comments

scripts/circle-test-backend.sh

@@ -10,9 +10,6 @@ function exit_if_fail {
     fi
 }
 
-echo "running go fmt"
-exit_if_fail test -z \"'$(gofmt -s -l ./pkg | tee /dev/stderr)'\"
-
 echo "building backend with install to cache pkgs"
 exit_if_fail time go install ./pkg/cmd/grafana-server