Add Rubocop exceptions

Because we dynamically create these probes, we just allow these unused
arguments.

lib/gitlab_exporter/database/remote_mirrors.rb

@@ -35,7 +35,7 @@ module GitLab
 
       # The prober which is called when gathering metrics
       class RemoteMirrorsProber
-        def initialize(opts, metrics: PrometheusMetrics.new, logger: nil)
+        def initialize(opts, metrics: PrometheusMetrics.new, logger: nil) # rubocop:disable Lint/UnusedMethodArgument
           @metrics = metrics
           @collector = RemoteMirrorsCollector.new(
             connection_string: opts[:connection_string],

lib/gitlab_exporter/database/row_count.rb

@@ -212,7 +212,7 @@ module GitLab
 
       # The prober which is called when gathering metrics
       class RowCountProber
-        def initialize(opts, metrics: PrometheusMetrics.new, logger: nil)
+        def initialize(opts, metrics: PrometheusMetrics.new, logger: nil) # rubocop:disable Lint/UnusedMethodArgument
           @metrics = metrics
           @collector = RowCountCollector.new(
             connection_string: opts[:connection_string],

lib/gitlab_exporter/git.rb

@@ -62,7 +62,7 @@ module GitLab
     # Optionally takes a metrics object which by default is a PrometheusMetrics, useful to change the
     # metrics writer to something else.
     class GitProber
-      def initialize(opts, metrics: PrometheusMetrics.new, logger: nil)
+      def initialize(opts, metrics: PrometheusMetrics.new, logger: nil) # rubocop:disable Lint/UnusedMethodArgument
         @metrics = metrics
         @labels = opts[:labels] || {}
         @git = Git.new(opts[:source])
@@ -85,7 +85,7 @@ module GitLab
 
     # A special prober for git processes
     class GitProcessProber
-      def initialize(opts, metrics: PrometheusMetrics.new, logger: nil)
+      def initialize(opts, metrics: PrometheusMetrics.new, logger: nil) # rubocop:disable Lint/UnusedMethodArgument
         @opts    = opts
         @metrics = metrics
       end

lib/gitlab_exporter/process.rb

@@ -59,7 +59,7 @@ module GitLab
 
     # Probes a process for info then writes metrics to a target
     class ProcessProber
-      def initialize(options, metrics: PrometheusMetrics.new, logger: nil)
+      def initialize(options, metrics: PrometheusMetrics.new, logger: nil) # rubocop:disable Lint/UnusedMethodArgument
         @metrics = metrics
         @name    = options[:name]
         @pids    = if options[:pid_or_pattern] =~ /^\d+$/