Multinode-HA Vespa Setup for Local Testing

[vicilliar]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  Testing improvement

• What is the current behavior? (You can also link to an open issue here)
  Current vespa setup only uses a single node.

• What is the new behavior (if this is a feature change)?
  We implement a multinode setup for local vespa, so we can simulate cloud shards and replicas.
  vespa_local.py start function now accepts --Shards and --Replicas as parameters. If Shards > 1 or Replicas > 0, multinode vespa setup is used. Multinode vespa setup has 3 config server nodes, max(2, total_content_nodes / 4) API nodes, and shards * (1 + replicas) content nodes.
  Unit test github workflow now accepts shards and replicas as parameters.
  Orchestrator workflow was created, which runs 4 unit tests setups:
  (1) 0 replicas, 1 shard
  (2) 1 replica, 1 shard
  (3) 0 replicas, 2 shards
  (4) 1 replica, 2 shards

Unit tests on multinode vespa will ignore the following directories: tests/integ_tests/core/inference, tests/integ_tests/processing, tests/integ_tests/s2_inference

Multinode vespa tests will use m6i.2xlarge instead of m6i.xlarge due to the higher memory usage from many vespa nodes. Config and API nodes are ~1gb and content nodes are ~500mb. A 9 node system (3 config, 2 API, 4 content) needs roughly 7gb for vespa alone.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  No

• Have unit tests been run against this PR? (Has there also been any additional testing?)
  In progress

• Related Python client changes (link commit/PR here)

• Related documentation changes (link commit/PR here)

• Other information:

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes/features)
• Docs have been added / updated (for bug fixes / features)