BigtableUploadService: increment start_slot to prevent rechecks

[CriesofCarrots]

Problem

Both solana-ledger-tool bigtable upload and the BigtableUploadService call solana_ledger::bigtable_upload::upload_confirmed_blocks() in a loop. However, they treat the return value (last slot checked) slightly differently.
Ledger tool increments the value to start checking on a fresh slot:

solana/ledger-tool/src/bigtable.rs

Line 83 in 70107e2

starting_slot = last_slot_checked.saturating_add(1);

The BigtableUploadService does not:

solana/ledger/src/bigtable_upload_service.rs

Line 120 in 70107e2

Ok(last_slot_uploaded) => start_slot = last_slot_uploaded,

This means that the BigtablUploadService is rechecking the starting slot of a range on every iteration of the loop. It's probably not a lot of wasted work, but not nothing.

I don't think there is a specific reason the BigtableUploadService doesn't increment; I think I probably just missed it when putting together #26030

Summary of Changes

Add increment

Incidentally, this change should be enough to fix the infinite loop in #33831, but I still want to land the fix in #33861.

[codecov]

Codecov Report

Merging #33870 (117f71f) into master (70107e2) will decrease coverage by 0.1%.
The diff coverage is 0.0%.

@@            Coverage Diff            @@
##           master   #33870     +/-   ##
=========================================
- Coverage    81.8%    81.8%   -0.1%     
=========================================
  Files         809      809             
  Lines      217824   217824             
=========================================
- Hits       178387   178327     -60     
- Misses      39437    39497     +60     

[ilya-bobyr]

I was also following this issue.
The change looks good to me.

[steviez]

Looks good to me and makes sense given that upload_confirmed_blocks() is inclusive of ending_slot:

solana/ledger/src/bigtable_upload.rs

Lines 61 to 67 in a799a90

	let blockstore_slots: Vec<_> = blockstore
	.rooted_slot_iterator(starting_slot)
	.map_err(|err| {
	format!("Failed to load entries starting from slot {starting_slot}: {err:?}")
	})?
	.take_while(|slot| *slot <= ending_slot)
	.collect();