Fix rules/functions.generage_manifest. (#9340)

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

Author: liushilongbuaa

rules/functions

@@ -197,7 +197,6 @@ define generate_manifest
     $(eval export tmpfs=$($(1).gz_CONTAINER_TMPFS))
     $(eval export config_cli_plugin=$($(1).gz_CLI_CONFIG_PLUGIN))
     $(eval export show_cli_plugin=$($(1).gz_CLI_SHOW_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