Fix rules/functions.generage_manifest. (sonic-net#9340)

Why I did it
Fix a bug in sonic debug image build. That bug is imported in the following PR: sonic-net#8920

rules/functions

@@ -198,7 +198,6 @@ define generate_manifest
     $(eval export config_cli_plugin=$($(1).gz_CLI_CONFIG_PLUGIN))
     $(eval export show_cli_plugin=$($(1).gz_CLI_SHOW_PLUGIN))
     $(eval export clear_cli_plugin=$($(1).gz_CLI_CLEAR_PLUGIN))
-    j2 $($*.gz_PATH)/Dockerfile$(2).j2 > $($(1).gz_PATH)/Dockerfile$(2)
     j2 --customize scripts/j2cli/json_filter.py files/build_templates/manifest.json.j2 > $($(1).gz_PATH)/manifest.common.json
     if [ -f $($*.gz_PATH)/manifest.part.json.j2 ]; then
         j2 --customize scripts/j2cli/json_filter.py $($(1).gz_PATH)/manifest.part.json.j2 > $($(1).gz_PATH)/manifest.part.json