fix(artifact test): remove 'developer-mode' arg for t3.micro

The change is presented in https://github.com/scylladb/scylla-cluster-tests/pull/6566/commits/
e49c4f4 added '--developer-mode' scylla argument for
t3.micro artifact test.

But later '--developer-mode' agrument was added to be default by
scylladb/scylla-machine-image#482.

As result
https://jenkins.scylladb.com/job/enterprise-2023.1/job/artifacts/job/artifacts-ami-t3_micro-test/
fails with error:

scylla[4265]: FATAL: Exception during startup, aborting: boost::wrapexcept<boost::program_options::
multiple_occurrences> (option '--developer-mode' cannot be specified more than once)

Remove '--developer-mode' arg.

(cherry picked from commit 3262654)

sdcm/cluster.py

@@ -1708,8 +1708,6 @@ def process_scylla_args(self, append_scylla_args=''):
             )
         if self.parent_cluster.params.get('db_nodes_shards_selection') == 'random':
             append_scylla_args += f" --smp {self.scylla_random_shards()}"
-        if self.db_node_instance_type == "t3.micro":
-            append_scylla_args += ' --developer-mode 1 '
 
         if append_scylla_args:
             self.log.debug("Append following args to scylla: `%s'", append_scylla_args)