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/where_.rs

@@ -1,5 +1,5 @@
 use nu_test_support::nu;
-#[cfg(feature = "database")]
+#[cfg(feature = "sqlite")]
 use nu_test_support::pipeline;
 
 #[test]
@@ -82,7 +82,7 @@ fn uses_optional_index_argument() {
     assert_eq!(actual.out, "[7, 8]");
 }
 
-#[cfg(feature = "database")]
+#[cfg(feature = "sqlite")]
 #[test]
 fn binary_operator_comparisons() {
     let actual = nu!(
@@ -151,7 +151,7 @@ fn binary_operator_comparisons() {
     assert_eq!(actual.out, "42");
 }
 
-#[cfg(feature = "database")]
+#[cfg(feature = "sqlite")]
 #[test]
 fn contains_operator() {
     let actual = nu!(