fix(collector): correct jsonpath alias parsing for rows missing path

[orangeCatDeveloper]

What's changed?

Fixes #3307.

A custom alias field $.status.containerStatuses[0].restartCount (monitor pod restart count, jsonPath parsing) returns an empty or wrong column. Example response, parseScript: $.items.*:

{"items": [
  {"metadata": {"name": "pod-a"}, "status": {"containerStatuses": [{"restartCount": 5}]}},
  {"metadata": {"name": "pod-b"}, "status": {"phase": "Pending"}},
  {"metadata": {"name": "pod-c"}, "status": {"containerStatuses": [{"restartCount": 2}]}}
]}

Two independent bugs. Both hit this user.

Bug 1: rows receive each other's values (HttpCollectImpl)

Problem. The alias column was filled by one global query, then distributed by row index:

query  $.items.*.status.containerStatuses[0].restartCount  →  [5, 2]

pod-b has no containerStatuses, and jayway skips it without a placeholder. Distributing [5, 2] by row index:

row	pod	gets	should be
0	pod-a	5	5
1	pod-b	2 (pod-c's value)	null
2	pod-c	nothing	2

Fix. Ask each row's own object instead of the whole response: new JsonPathParser.parseRowWithJsonPath(rowObject, alias). A row that lacks the path returns an empty list → NULL cell. No cross-row indexing, nothing to misalign.

Bug 2: the calculates step silently eats the value (MetricsCollect)

Problem. calculates: rc=$.status.containerStatuses[0].restartCount must be classified: is the right side a column reference or a formula? The old rule was "if it compiles as JEXL, it's a formula". This path does compile — JEXL reads [0] as array access on a variable named $.status.containerStatuses. That variable doesn't exist, so it evaluates to null with no log. The column stays empty even when Bug 1 is fixed.

Fix. Before compiling, check: right side exactly equals one of the metric's aliasFields? Then it is by definition a column reference → map it directly, skip JEXL. Real formulas keep working — docker's cpu_delta=$.cpu_stats... - $.precpu_stats... doesn't equal any single aliasField.

Test plan

• Unit tests reproduce both bugs (red before the fix, green after): HttpCollectImplTest, MetricsCollectTest, JsonPathParserTest. Full collector suites pass.
• End-to-end on a local instance with a mocked pods API, same monitor, only collector jars swapped: before → rc all null; after → 5 / null / 2.
• Regression: official spring_gateway (profile=$.activeProfiles[0]) and docker (name=$.Names[0]) monitors return identical values before and after.

Checklist

• I have read the Contributing Guide
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

Add or update API

• I have added the necessary e2e tests and all cases have passed.