Feature cleanup (#7182)

Following up on #7180 with some feature cleanup:

- Move the `database` feature from `plugin` to `default`
- Rename the `database` feature to `sqlite`
- Remove `--features=extra` from a lot of scripts etc. 
- No need to specify this, the `extra` feature is now the same as the
default feature set
- Remove the now-redundant 2nd Ubuntu test run

crates/nu-command/tests/commands/open.rs

@@ -108,7 +108,7 @@ fn parses_more_bson_complexity() {
 // │ 4 │      │
 // ╰───┴──────╯
 
-#[cfg(feature = "database")]
+#[cfg(feature = "sqlite")]
 #[test]
 fn parses_sqlite() {
     let actual = nu!(
@@ -123,7 +123,7 @@ fn parses_sqlite() {
     assert_eq!(actual.out, "3");
 }
 
-#[cfg(feature = "database")]
+#[cfg(feature = "sqlite")]
 #[test]
 fn parses_sqlite_get_column_name() {
     let actual = nu!(