[exporter/opensearchexporter] Prevent dotted-attribute mapping conflicts

[singhvibhanshu]

Description

This PR prevents dotted-attribute mapping conflicts in the OpenSearch exporter.

OpenSearch expands dots in JSON field names into nested objects during dynamic mapping. OTel attributes are a flat namespace, so an attribute map containing both a concrete key (e.g. code.function) and a longer key that uses it as an object prefix (e.g. code.function.name) made OpenSearch try to map attributes.code.function as both a value and an object, rejecting the document with a mapper_parsing_exception. This commonly happens while migrating between semantic-convention versions.

The conflict is resolved in two complementary ways:

• The conflicting concrete value is always relocated under a .value sub-key (code.function becomes code.function.value) for span, event, link, log-record, metric data-point, exemplar and instrumentation-scope attributes in the ss4o and otel-v1 mapping modes. Only documents OpenSearch would otherwise reject are changed.
• mapping.manage_index_template is now supported in ss4o mode, installing traces and logs index templates that map attribute bags as flat_object so OpenSearch stops expanding dotted attribute keys. This deterministically avoids conflicts across documents. Since flat_object indexes values as strings, the option is opt-in and defaults to false.

Link to tracking issue

Fixes #47465

Testing

Tuned.

Documentation

Tuned.

Authorship

• I, a human, wrote this pull request description myself.