Enhance parallel foreign scan support #494

Job	Run time
check-skip	2s
Build Apache Cloudberry DEB	14m 54s
prepare-test-matrix-deb	3s
pax-ic-deb-good-opt-off	23m 35s
ic-deb-good-opt-off	26m 5s
DEB Install Test Apache Cloudberry	1m 17s
pax-ic-deb-good-opt-on	27m 38s
ic-deb-good-opt-on	35m 30s
ic-cbdb-parallel	28m 38s
ic-deb-contrib	4m 37s
ic-deb-gpcontrib	4m 0s
Generate Apache Cloudberry Build Report	3s
	2h 46m 22s

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