### CI Link

https://gradle-enterprise.elastic.co/s/dvtf7swsnm44o

### Repro line

./gradlew ':x-pack:plugin:autoscaling:test' --tests "org.elasticsearch.xpack.autoscaling.capacity.AutoscalingCalculateCapacityServiceTests.testContext" -Dtests.seed=15E8E10F966ECA7A -Dtests.locale=be-BY -Dtests.timezone=America/Noronha -Druntime.java=17	

### Does it reproduce?

Yes

### Applicable branches

main

### Failure history

https://gradle-enterprise.elastic.co/scans/tests?search.timeZoneId=Europe/Rome&tests.container=org.elasticsearch.xpack.autoscaling.capacity.AutoscalingCalculateCapacityServiceTests&tests.test=testContext

### Failure excerpt

```
org.elasticsearch.xpack.autoscaling.capacity.AutoscalingCalculateCapacityServiceTests > testContext FAILED
    java.lang.NullPointerException: Cannot invoke "org.elasticsearch.xpack.autoscaling.capacity.AutoscalingCapacity.node()" because the return value of "org.elasticsearch.xpack.autoscaling.capacity.AutoscalingDeciderContext.currentCapacity()" is null
        at __randomizedtesting.SeedInfo.seed([EB0EF2643F2D6C41:7D3B02C92A094B8F]:0)
        at org.elasticsearch.xpack.autoscaling.capacity.AutoscalingCalculateCapacityServiceTests.testContext(AutoscalingCalculateCapacityServiceTests.java:225)
```
x-pack/plugin/autoscaling/src/test/java/org/elasticsearch/xpack/autoscaling/capacity/AutoscalingCalculateCapacityServiceTests.java
randomRoles(),
            new TreeMap<>(
                Map.of(FixedAutoscalingDeciderService.NAME, Settings.builder().put(badSettingName, randomAlphaOfLength(1)).build())
            )
        );
        IllegalArgumentException exception = expectThrows(IllegalArgumentException.class, () -> service.validate(policy));
        assertThat(
            exception.getMessage(),
            equalTo("unknown setting [" + badSettingName + "] for decider [" + FixedAutoscalingDeciderService.NAME + "]")
        );
    }
    public void testValidateSettingValue() {
        AutoscalingCalculateCapacityService service = new AutoscalingCalculateCapacityService(Set.of(new FixedAutoscalingDeciderService()));
        String value = randomValueOtherThanMany(s -> Character.isDigit(s.charAt(0)), () -> randomAlphaOfLength(5));
        AutoscalingPolicy policy = new AutoscalingPolicy(
            randomAlphaOfLength(8),
            randomRoles(),
            new TreeMap<>(
                Map.of(
                    FixedAutoscalingDeciderService.NAME,
                    Settings.builder().put(FixedAutoscalingDeciderService.STORAGE.getKey(), value).build()
                )
            )
        );
        IllegalArgumentException exception = expectThrows(IllegalArgumentException.class, () -> service.validate(policy));
        assertThat(exception.getMessage(), containsString("[" + value + "]"));
        assertThat(exception.getMessage(), containsString("[" + FixedAutoscalingDeciderService.STORAGE.getKey() + "]"));
    }
}