junos: add lab for OSPF process-level topology default metric

[dhalperi]

Single vJunos-router 25.4R1.12 node with a cEOS OSPF/OSPF3 peer, testing
the undocumented set protocols ospf topology default metric 65450.
Junos rejects it with a syntax error at metric for OSPF and at
topology for OSPF3, in the master instance and in a virtual-router,
whether entered with set, load set terminal, or load merge terminal. The load commands keep the valid prefix, so a bulk load
commits a bare topology default;, which has no operational effect.
The documented interface-level topology default metric (OSPF) and
metric (OSPF3) are the positive control; the collected snapshot has
both, plus the bare process-level stanza, which Batfish reports as
unrecognized syntax.

---

Prompt:

Using a real Junos device, validate whether Junos accepts this undocumented process-level command:

  set protocols ospf topology default metric 65450

  Test OSPF and OSPF3 at the process level, including within a routing instance if practical. Use the documented interface-
  level topology metric syntax as a positive control. Determine whether the process-level command commits, appears in
  normalized configuration output, and has any observable operational effect.

  Record the platform, exact Junos version, commands, commit-check output, normalized configuration, and relevant operational
  output. Use an isolated configuration and restore the device afterward.

  Add the anonymized results to batfish/lab-validation and open a PR. Do not modify Batfish.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.59%. Comparing base (2a77265) to head (7221ee6).

Additional details and impacted files

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  Coverage   83.59%   83.59%           
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  Files          96       96           
  Lines        4706     4706           
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  Hits         3934     3934           
  Misses        772      772           

Flag	Coverage Δ
unittests	83.59% <ø> (ø)

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