[Release] 02-source.sh executed with default `SOURCE_UPLOAD` and default `SOURCE_VOTE` fails

[raulcd]

Describe the bug, including details regarding any error messages, version, and platform.

On the following PR:

• GH-49248: [Release] Include checksum in vote email #49249

We added the ability to incorporate the sha512 to the Vote email automatically. The problem is that the script currently has a dual purpose.
Upload sources and the threading vote email.

When uploading sources we delete the artifacts folder:

arrow/dev/release/02-source.sh

Lines 92 to 94 in 41035d4

	# clean up
	rm -rf artifacts
	rm -rf tmp

But unless executed with SOURCE_VOTE=0 we fail if the folder isn't found:

arrow/dev/release/02-source.sh

Lines 133 to 136 in 41035d4

	# Read the checksum so we can include it in the vote thread email.
	sha512_path="artifacts/${tarball}.sha512"
	[[ -f "${sha512_path}" ]] || { echo "Error: ${sha512_path} must exist"; exit 1; }
	tarball_hash=$(cat "${sha512_path}" | awk '{print $1}')

Currently on the documentation we don't specify that we should run with SOURCE_VOTE=0 on this first execution:

arrow/docs/source/developers/release.rst

Lines 236 to 240 in 41035d4

	# Waits for previous workflows to finish and uploads source and signatures to SVN.
	#
	# NOTE: This must be run by a PMC member
	# NOTE: You need to have GitHub CLI installed to run this script.
	dev/release/02-source.sh <version> <rc-number>

Following current release guidelines we see the following (non-harmful error) locally:

$ dev/release/02-source.sh 24.0.0 0
Preparing source for tag apache-arrow-24.0.0-rc0
Using commit 31b4b6c0a0a7e7c117312d285541a21446675ec6
Looking for GitHub Actions workflow on apache/arrow:apache-arrow-24.0.0-rc0
Waiting for run to start...
Found GitHub Actions workflow with ID: 24404382525
Run RC (24404382525) has already completed with 'success'
OK
No unapproved licenses
Checked out revision 83789.
A         tmp/apache-arrow-24.0.0-rc0
A  (bin)  tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz
A         tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz.sha512
A         tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz.asc
A         tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz.sha256
Adding         tmp/apache-arrow-24.0.0-rc0
Adding  (bin)  tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz
Adding         tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz.asc
Adding         tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz.sha256
Adding         tmp/apache-arrow-24.0.0-rc0/apache-arrow-24.0.0.tar.gz.sha512
Transmitting file data ....done
Committing transaction...
Committed revision 83790.
Success! The release candidate is available here:
  https://dist.apache.org/repos/dist/dev/arrow/apache-arrow-24.0.0-rc0

Commit SHA1: 31b4b6c0a0a7e7c117312d285541a21446675ec6

  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed
100    157 100     39 100    118     94    286                              0
  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed
100  27494 100  27494   0      0  55918      0                              0
Error: artifacts/apache-arrow-24.0.0.tar.gz.sha512 must exist

We should probably have a final clean up step that deletes the artifacts folder.

Component(s)

Release