testing: Disable flaky lightclient tests

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

Cargo.lock

@@ -780,6 +780,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "cfg_aliases"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77e53693616d3075149f4ead59bdeecd204ac6b8192d8969757601b74bddf00f"
+
 [[package]]
 name = "chacha20"
 version = "0.9.1"
@@ -2256,6 +2262,7 @@ name = "integration-tests"
 version = "0.34.0"
 dependencies = [
  "assert_matches",
+ "cfg_aliases",
  "frame-metadata 16.0.0",
  "futures",
  "hex",