AttributesMap counts attribute overwrites as dropped attributes

Describe the bug
AttributesMap.put() increments totalAddedValues even when it overwrites an existing key. SdkSpan.toSpanData() exposes that counter as SpanData.getTotalAttributeCount(), and the OTLP marshalers serialize getTotalAttributeCount() - getAttributes().size() as dropped_attributes_count, so every overwrite is reported as a drop.

Steps to reproduce

Span span = SdkTracerProvider.builder().build().get("t").spanBuilder("s").startSpan();
span.setAttribute("http.route", "/a");
span.setAttribute("http.route", "/b");
SpanData data = ((ReadableSpan) span).toSpanData();

What did you expect to see?
data.getTotalAttributeCount() == 1 and dropped_attributes_count=0 over OTLP. The spec only allows discarding attributes when a limit is exceeded and defines same-key sets as overwrites (https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/common/README.md#attribute-limits); the proto comment says 0 means nothing was dropped. opentelemetry-go (addOverCapAttrs) and opentelemetry-python (BoundedAttributes) do not count overwrites as drops.

What did you see instead?
data.getTotalAttributeCount() == 2 while data.getAttributes().size() == 1, so the exported span carries dropped_attributes_count=1. Cause: the increment in AttributesMap.put() (sdk/common/src/main/java/io/opentelemetry/sdk/common/internal/AttributesMap.java line 123) runs before the existing-name check. Log records (SdkReadWriteLogRecord) and recordException events share this path. Related: #7142 fixed a different dropped-count inaccuracy in the same class.

What version and what artifacts are you using?
Artifacts: opentelemetry-sdk-common, opentelemetry-sdk-trace, opentelemetry-exporter-otlp
Version: main @ 509182e4b
How did you reference these artifacts? N/A

Environment
Compiler: Temurin 21
OS: N/A

Additional context
N/A

Start in sdk/common/src/main/java/io/opentelemetry/sdk/common/internal/AttributesMap.java at the counter update and existing-name check. Trace how SdkSpan.toSpanData(), SdkReadWriteLogRecord, recordException events, and the OTLP marshalers use the count. Reproduce the overwrite example and verify that total attributes remains 1 and dropped_attributes_count is 0.