Remove _snap_log_name and put back comments from #9956 (#10385)

https://github.com/certbot/certbot/pull/9956/ was accidentally merged,
so we rolled the thousand commits back, and put them back in
https://github.com/certbot/certbot/pull/9983/

In the process, commits
7d3ceb27b6
and
f62eab640e
were lost. The comment in `snapcraft.yaml` is superseded by
https://github.com/certbot/certbot/pull/10384, so let's just reapply the
remaining changes to `build_remote.py` and `snapcraft.yaml`.

snap/snapcraft.yaml

@@ -123,6 +123,7 @@ parts:
       grep -v python-augeas "${CRAFT_PART_SRC}/tools/requirements.txt" >> "${CRAFT_PART_SRC}/snap-constraints.txt"
       craftctl set version=$(grep -oP "__version__ = '\K.*(?=')" "${CRAFT_PART_SRC}/certbot/src/certbot/__init__.py")
     build-attributes:
+      # https://snapcraft.io/docs/how-to-classic#fix-linter-warnings-by-patching-elf-binaries
       - enable-patchelf
   shared-metadata:
     plugin: dump

tools/snap/build_remote.py

@@ -42,10 +42,6 @@ PLUGINS = [basename(path) for path in glob.glob(join(CERTBOT_DIR, 'certbot-dns-*
 print = functools.partial(print, flush=True)
 
 
-def _snap_log_name(target: str, arch: str):
-    return f'{target}_{arch}.txt'
-
-
 def _execute_build(
         target: str, archs: Set[str], status: Dict[str, Dict[str, str]],
         workspace: str, output_lock: Lock) -> Tuple[int, List[str]]:
@@ -109,7 +105,9 @@ def _build_snap(
         workspace = CERTBOT_DIR
     else:
         workspace = join(CERTBOT_DIR, target)
-        # init and commit git repo in workspace
+        # Init and commit git repo in workspace. This is necessary starting in core24
+        # as "Projects must be at the top level of a git repository"
+        # https://snapcraft.io/docs/migrate-core24#remote-build
         subprocess.run(['git', 'init'], capture_output=True, check=True, cwd=workspace)
         subprocess.run(['git', 'add', '-A'], capture_output=True, check=True, cwd=workspace)
         subprocess.run(['git', 'commit', '-m', 'init'], capture_output=True, check=True, cwd=workspace)
@@ -125,6 +123,8 @@ def _build_snap(
             print(f'Build {target} for {",".join(archs)} (attempt {4-retry}/3) ended with '
                   f'exit code {exit_code}.')
 
+            # This output may change, and is set by
+            # https://github.com/canonical/snapcraft/blob/8ab7fd0c8a1d3f13045bec41a6e0158c063faa9b/snapcraft/commands/remote.py#L278
             failed_archs = [arch for arch in archs if status[target][arch] != 'Succeeded']
             # If the command failed or any architecture wasn't built
             # successfully, let's try to print all the output about the problem
@@ -157,6 +157,8 @@ def _build_snap(
 def _extract_state(project: str, output: str, status: Dict[str, Dict[str, str]]) -> None:
     state = status[project]
 
+    # This output may change, and is set by
+    # https://github.com/canonical/snapcraft/blob/8ab7fd0c8a1d3f13045bec41a6e0158c063faa9b/snapcraft/commands/remote.py#L218
     if "Starting new build" in output:
         for arch in state.keys():
             state[arch] = "Starting new build"
@@ -204,6 +206,9 @@ def _dump_failed_build_logs(
         if result != 'Succeeded':
             failures = True
 
+            # log name is no longer set deterministically as target_arch.txt
+            # this will still result in a single output though, as we're filtering
+            # by target above and arch here
             build_output_path = [log_name for log_name in logs_list if arch in log_name]
             if not build_output_path:
                 build_output = 'No output has been dumped by snapcraft remote-build.'