docs: update few more documentation issues

[doehyunbaek]

I found two documentation issues that still appear to be present on current main as of 2edca39.

1. OTLP service connections are omitted from SSL support lists

The Docker Compose SSL support section lists supported service connections, but omits OpenTelemetry/OTLP logging, metrics, and tracing are omitted from dev-services.adoc and testcontainers.adoc

Introduced by:

• 0627214
• d7f86aa
• 166b88b

2. External configuration docs show invalid @Value syntax

The external configuration docs use @Value(${"my.service.enabled"}):

spring-boot/documentation/spring-boot-docs/src/docs/antora/modules/reference/pages/features/external-config.adoc

Line 958 in 2edca39

Concretely, this prevents you to use `@Value(${"my.service.enabled"})` or `my.service.enabled` as a placeholder in configuration properties without explicitly providing a default.

But Java annotation values must be string literals. The placeholder should be inside the string:

@Value("${my.service.enabled}")

Introduced by:

• a5338e5

This PR fixes the above two issues.