Fix misc. linter issues (comments, variable naming, etc.)

We've accumulated a few linter issues around comments and a couple of
variable names.

While none of them is major, this patch cleans them up so it's easier to
go through the linter output, and we can start being more strict about
it.

.cirrus.yml

@@ -37,8 +37,7 @@ lint_task:
           - linters:
               - staticcheck
             # SA1015: time.Tick leaks but it's ok on endless functions.
-            # SA1019: BuildNameToCertificate deprecation, remove on Go >= 1.14.
-            text: "SA1015:|SA1019:"
+            text: "SA1015:"
         exclude-use-default: true
   lint_config_file:
     path: /tmp/lint.yml