Implement series_key in a more efficient way

[mgattozzi]

As part of #25596 I changed the series_key method to look like this

influxdb/influxdb3_catalog/src/catalog.rs

Lines 1137 to 1142 in 719d9c4

	pub fn series_key(&self) -> Vec<String> {
	self.series_key
	.iter()
	.map(|k| self.column_id_to_name_unchecked(k).to_string())
	.collect()
	}

This isn't the most efficient as we're changing an Arc<str> into an owned String and creating a Vec. However, the comparison where it's used in is comparing against a Vec<&str>. We can't use the lookup method on the ColumnId to get an Arc<str> and turn it into an &str without facing issues with the type system. We also can't return a slice easily either.

Our best bet is to cache the names of the columns as a Vec<String> in the TableDefinition and to return an &[&str] instead of a Vec<String>. Since this is a bit invasive I've split this off into a separate ticket.