build: don't distribute tests_config.py

This file is dynamically generated by configure based on the platform,
it doesn't belong in the distribution archive.

Fixes #6929.

Makefile.am

@@ -213,7 +213,7 @@ endif
 
 dist_noinst_SCRIPTS = autogen.sh
 
-EXTRA_DIST = $(top_srcdir)/share/genbuild.sh qa/pull-tester/rpc-tests.py qa/pull-tester/tests_config.py qa/rpc-tests $(DIST_DOCS) $(WINDOWS_PACKAGING) $(OSX_PACKAGING)
+EXTRA_DIST = $(top_srcdir)/share/genbuild.sh qa/pull-tester/rpc-tests.py qa/rpc-tests $(DIST_DOCS) $(WINDOWS_PACKAGING) $(OSX_PACKAGING)
 
 CLEANFILES = $(OSX_DMG) $(BITCOIN_WIN_INSTALLER)