Disable flaky tests reported in 5972/5973/5974 (#5976)

Disable flaky tests reported in:
#5972 
#5973 
#5974

Author: pepoviola

.gitlab/pipeline/zombienet/polkadot.yml

@@ -94,7 +94,7 @@ zombienet-polkadot-functional-0002-parachains-disputes:
       --local-dir="${LOCAL_DIR}/functional"
       --test="0002-parachains-disputes.zndsl"
 
-zombienet-polkadot-functional-0003-beefy-and-mmr:
+.zombienet-polkadot-functional-0003-beefy-and-mmr:
   extends:
     - .zombienet-polkadot-common
   script:
@@ -190,7 +190,7 @@ zombienet-polkadot-elastic-scaling-0002-elastic-scaling-doesnt-break-parachains:
       --local-dir="${LOCAL_DIR}/elastic_scaling"
       --test="0002-elastic-scaling-doesnt-break-parachains.zndsl"
 
-zombienet-polkadot-functional-0012-spam-statement-distribution-requests:
+.zombienet-polkadot-functional-0012-spam-statement-distribution-requests:
   extends:
     - .zombienet-polkadot-common
   script:
@@ -277,7 +277,7 @@ zombienet-polkadot-smoke-0002-parachains-parachains-upgrade-smoke:
       --local-dir="${LOCAL_DIR}/smoke"
       --test="0002-parachains-upgrade-smoke-test.zndsl"
 
-zombienet-polkadot-smoke-0003-deregister-register-validator:
+.zombienet-polkadot-smoke-0003-deregister-register-validator:
   extends:
     - .zombienet-polkadot-common
   script:

.gitlab/pipeline/zombienet/substrate.yml

@@ -70,7 +70,7 @@ zombienet-substrate-0001-basic-warp-sync:
       --local-dir="${LOCAL_DIR}/0001-basic-warp-sync"
       --test="test-warp-sync.zndsl"
 
-zombienet-substrate-0002-validators-warp-sync:
+.zombienet-substrate-0002-validators-warp-sync:
   extends:
     - .zombienet-substrate-warp-sync-common
   before_script: