Remove psi from gpMgmt Makefile

The psi package is no longer installed anywhere, so remove the target
from the Makefile.

Reported-by: Shaoqi Bai
Discussion: https://github.com/greenplum-db/gpdb/pull/8179
Reviewed by Bradford Boyle, Kalen Krempely, Jamie McAtamney and
many more

(cherry picked from commit 832896ff)

gpMgmt/bin/Makefile

@@ -125,19 +125,6 @@ subprocess32:
 		  cp -f $(PYLIB_SRC)/subprocess32/build/lib.*/* $(PYLIB_DIR)/;  \
 	  fi
 
-#
-# PSI
-PSI_DIR=PSI-$(PSI_VERSION)
-
- psi:
-	@echo "--- psi"
-ifeq "$(findstring $(BLD_ARCH),aix7_ppc_64 )" ""
-	cd $(PYLIB_SRC)/ && $(TAR) xzf $(PSI_DIR).tar.gz
-	cd $(PYLIB_SRC)/$(PSI_DIR)/ && CC="$(CC)" python setup.py build
-	cp -r $(PYLIB_SRC)/$(PSI_DIR)/build/lib.*/psi $(PYLIB_DIR)
-endif
-
-
 #
 # PSUTIL
 #