while parse uri, overwrite the db_name with default

[PowderLi]

/kind bug
milvus #26833
milvus #26834

		default value	user case1(as bug described)	user case2	user case 3	user case4
MilvusClient's arguments	uri	http://localhost:19530	http://localhost:19530	http://localhost:19530/test	http://localhost:19530/test	http://localhost:19530/test
	db_name		test		default	test
connect with milvus server		found uri without dbname, use "default"	found uri without dbname, use "default"	found uri with dbname "test"	found uri with dbname "test"	found uri with dbname "test"
result		correct	db_name didn't work	corrent	uri priority higher	corrent
how to fix			use db_name "test"

[czs007]

/approve
/lgtm

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