Add observability to Bedrock Titan Embedding model

[PSriVarshan]

Description

This PR introduces observability to the Bedrock Titan Embedding Model by adding Micrometer Observation around the embedding API call. This ensures consistent metrics and tracing support in accordance with the Spring AI observability pattern.

• Observations are added using ObservationRegistry.
• Keys include model, input_type, and input_length.

Changes

• Modified: BedrockTitanEmbeddingModel.java to wrap the API call in Observation.createNotStarted().observe(...)

Related Issue

Fixes #2983

Checklist

• Follows project coding standards
• Observability uses ObservationRegistry
• Validated locally with sample embedding call

Do let me know if there are any further modifications required within the PR

[markpollack]

Thanks. A few things to clean up in the PR.

1. it dosn't compile - need to a) run ./mvnw spring-javaformat:apply
2. BedrockTitanEmbeddingModelIT has a compile error since the constructor changed.

adding

@Autowired
TestObservationRegistry observationRegistry;

and changing the bean def to be

		@Bean
		public BedrockTitanEmbeddingModel titanEmbedding(TitanEmbeddingBedrockApi titanEmbeddingApi, TestObservationRegistry observationRegistry) {
			return new BedrockTitanEmbeddingModel(titanEmbeddingApi, observationRegistry);
		}

Also, you can use OpenAiEmbeddingModelObservationIT to copy over other tests related to observability.

[PSriVarshan]

I think now the branch is fully ready and optimal. Thanks a ton for the guidance @markpollack. Waiting for your further guidance.

[ilayaperumalg]

@PSriVarshan Thanks for the PR and following up with the changes.

[ilayaperumalg]

We don't need an explicit version here.

[ilayaperumalg]

Similar to other auto configurations, we don't provide the default ObservationRegistry instead provide NOOP registry when none provided. Will update the PR when merging.

[ilayaperumalg]

Squashed, addressed the review comments and pushed the changes via a36c709