fix(ci): fail meta using jq halt_error if data is unexpectedly missing (#11151)

## Problem
When the githb API is having problems, we might not get data back, and
are happily setting vars as empty. This causes problems down the line.
See
https://github.com/neondatabase/neon/actions/runs/13718859397/job/38381946590?pr=11132#step:5:1
for example.

## Summary of changes
Fail the `meta` job if we don't get expected data back from github.

.github/scripts/previous-releases.jq

@@ -17,6 +17,12 @@
 ({};
  .[$entry.component] |= (if . == null or $entry.version > .version then $entry else . end))
 
+# Ensure that each component exists, or fail
+| (["storage", "compute", "proxy"] - (keys)) as $missing
+| if ($missing | length) > 0 then
+    "Error: Found no release for \($missing | join(", "))!\n" | halt_error(1)
+  else . end
+
 # Convert the resulting object into an array of formatted strings
 | to_entries
 | map("\(.key)=\(.value.full)")