### Description

We've been working on the health API for a while and the breaking changes have slowed to the point where we can promote the API away from the `/_internal` categorization.
qa/smoke-test-http/src/javaRestTest/java/org/elasticsearch/http/HealthRestCancellationIT.java
private final Semaphore operationBlock;
        BlockingHealthIndicator(Semaphore operationBlock) {
            this.operationBlock = operationBlock;
        }
        @Override
        public String name() {
            return BlockingHealthPlugin.class.getSimpleName();
        }
        @Override
        public HealthIndicatorResult calculate(boolean verbose, int maxAffectedResourcesCount, HealthInfo healthInfo) {
            try {
                operationBlock.acquire();
            } catch (InterruptedException e) {
                throw new AssertionError(e);
            }
            operationBlock.release();
            return new HealthIndicatorResult(
                name(),
                HealthStatus.GREEN,
                "testing",
                SimpleHealthIndicatorDetails.EMPTY,
                List.of(),
                List.of()
            );
        }
    }
}