should reset session space after Space not existed

[nebula-bots]

there're two session, sessionA and sessionB

1. sessionA: create spaceA, and then use space.
2. sessionB: drop the spaceA
3. sessionA: create tag in spaceA

expected result:

1. raise a Space not existed error.
2. the space name in resultSet should be ""

actual result:

1. raise a Space not existed error.
2. the space name in resultSet is still "spaceA"

space name is still "spaceA"

[Aiee]

We might need to add a new error code to distinguish if the SPACE_NOT_FOUND is returned by a USE statement or other statements.

For example, for query like use space_1; create tag t1(), if space_1 was dropped before executing create tag t1(), the session space should be reset. If space_1 was dropped before executing use space_1, the space should remain the same.

This will be regarded as a known issue for now.

[Sophie-Xie]

Discuss it with @MuYiYong @HarrisChu: we will not fix it.