Clear string-tracking hash table when ByteView deduplication is enabled

[shanesveller]

Which issue does this PR close?

Closes #6384.

Rationale for this change

The panic observed in #6384 was within StringViewBuilder::get_value, because the string_tracker hash table was not reset as part of finish():

arrow-rs/arrow-array/src/builder/generic_bytes_view_builder.rs

Lines 365 to 373 in e838e62

	pub fn finish(&mut self) -> GenericByteViewArray<T> {
	self.flush_in_progress();
	let completed = std::mem::take(&mut self.completed);
	let len = self.views_builder.len();
	let views = ScalarBuffer::new(self.views_builder.finish(), 0, len);
	let nulls = self.null_buffer_builder.finish();
	// SAFETY: valid by construction
	unsafe { GenericByteViewArray::new_unchecked(views, completed, nulls) }
	}

If the builder saw continued use, and append_value was called with a previously-observed value, the hash table would return an index to a now-emptied buffer after slicing into it here:

arrow-rs/arrow-array/src/builder/generic_bytes_view_builder.rs

Lines 257 to 259 in e838e62

	pub fn get_value(&self, index: usize) -> &[u8] {
	let view = self.views_builder.as_slice().get(index).unwrap();
	let len = *view as u32;

What changes are included in this PR?

Builders will now clear the string_tracker hash-table as part of a revised finish definition.

Are there any user-facing changes?

Not to my knowledge.

[shanesveller]

ℹ️ This is my first PR to the Arrow repository as well as to any Apache repository. I've reviewed the CONTRIBUTING documents as well as I can after watching day 1 of RustConf, but if I've overlooked anything or need to make any adjustments to the implementation, commit message, etc. to align with the project standards, I'm very happy to do so.

[shanesveller]

Please let me know if a regression test isn't needed for a simple change like this, I'm fine with dropping it if that's preferred.

[alamb]

Regression tests are always appreciated and we try to make then required.

Thank you for doing this @shanesveller

[tustvold]

All looks good to me, thank you

[alamb]

FYI @XiangpengHao

[XiangpengHao]

look good to me, nice catch!

[alamb]

❤️ Thanks @shanesveller @tustvold and @XiangpengHao

[alamb]

Regression tests are always appreciated and we try to make then required.

Thank you for doing this @shanesveller

[alamb]

ℹ️ This is my first PR to the Arrow repository as well as to any Apache repository.

Welcome and thank you