leak tests: mark some fast-import tests as passing with SANITIZE=leak

Mark some tests that match "*fast-import*" as passing when git is
compiled with SANITIZE=leak. They'll now be listed as running under
the "GIT_TEST_PASSING_SANITIZE_LEAK=true" test mode (the "linux-leaks"
CI target).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9302-fast-import-unpack-limit.sh

@@ -1,5 +1,7 @@
 #!/bin/sh
 test_description='test git fast-import unpack limit'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'create loose objects on import' '

t/t9303-fast-import-compression.sh

@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='compression setting of fast-import utility'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 import_large () {