Drop test environment for confluent 5.4 since the docker image has been removed (DataDog#20968)

Author: AAraKKe

confluent_platform/hatch.toml

@@ -2,14 +2,10 @@
 
 [[envs.default.matrix]]
 python = ["3.12"]
-version = ["5.4", "6.2"]
+version = ["6.2"]
 
 [envs.default.overrides]
 matrix.version.env-vars = [
-  { key = "CONFLUENT_VERSION", value = "5.4.0", if = ["5.4"] },
-  { key = "CONFLUENT_VERSION_CONNECT", value = "0.2.0-5.4.0", if = ["5.4"] },
-  { key = "CONFLUENT_KSQLDB_NAME", value = "ksql", if = ["5.4"] },
-
   { key = "CONFLUENT_VERSION", value = "6.2.0", if = ["6.2"] },
   { key = "CONFLUENT_VERSION_CONNECT", value = "0.5.0-6.2.0", if = ["6.2"] },
   { key = "CONFLUENT_KSQLDB_NAME", value = "ksqldb", if = ["6.2"] },