[JOOQ] MetricsDSLContext - fetchExists doesn't report provided tags

[eye-dee]

Describe the bug
When using dsl.tag("tag", "value").fetchExists(SOME_TABLE, SOME_CONDITION);, the expected metric is not reported. The issue arises because the tag value is not being passed correctly to the query listener. Internally, the following code is executed:

fetchExists(selectOne().from(table).where(condition));

This causes query tags to be removed from the thread-local context prematurely. Specifically, in MetricsDSLContext, the time() method clears the tags before they're available to the JooqExecuteListener:

public Configuration time(Configuration c) {
    Iterable<Tag> queryTags = contextTags.get();
    contextTags.remove();
    return derive(c, () -> new JooqExecuteListener(registry, tags, () -> queryTags));
}

As a result, no tags are attached to the query metrics when fetchExists is used.

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Environment

• Micrometer version: 1.15.2
• Micrometer registry: prometheus
• OS: macOS
• Java version: OpenJDK 21

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To Reproduce
Use the following code snippet:

dsl.tag("tag", "value")
   .fetchExists(SOME_TABLE, SOME_CONDITION);

Observe that no query metric with the tag "tag" = "value" is reported.

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Expected behavior
The tag provided via dsl.tag(...) should be passed to the query listener, and metrics should be reported with the specified tag.

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Additional context
It appears that fetchExists internally rewrites the query and performs a new one via selectOne().from(...), causing the tags to be cleared before metric recording. This issue may also affect other similar high-level shortcut methods if they internally trigger a new execution context.