[rb] Use Bazel JDK when starting server

This ensures the server is not started with a system JDK which might be
missing, outdated or simply inaccessible due to Bazel test sandboxing.

rb/lib/selenium/server.rb

@@ -241,7 +241,7 @@ def process
         # extract any additional_args that start with -D as options
         properties = @additional_args.dup - @additional_args.delete_if { |arg| arg[/^-D/] }
         args = ['-jar', @jar, @role, '--port', @port.to_s]
-        server_command = ['java'] + properties + args + @additional_args
+        server_command = [java_bin] + properties + args + @additional_args
         cp = WebDriver::ChildProcess.build(*server_command)
 
         if @log.is_a?(String)
@@ -256,6 +256,14 @@ def process
       end
     end
 
+    def java_bin
+      if ENV.key?('BAZEL_TEST') && ENV.key?('JAVA_HOME')
+        "#{ENV['JAVA_HOME']}/bin/java"
+      else
+        'java'
+      end
+    end
+
     def poll_for_service
       return if socket.connected?