Switch approach to asserting not null when using satisfies()

[jaydeluca]

While working on metadata for couchbase, I found that some of the assertions weren't working correctly. These assertions should have actually failed because the test suite wasn't setting the flag to enable experimental attributes.

In this example, it doesn't work as expected because val is an StringAssert object and is never null, so the test passes:

  @Test
  void test() {
    testing().runWithSpan("test", () -> {});

    testing().waitAndAssertTraces(
        traceAssert -> traceAssert.hasSpansSatisfyingExactly(
            span -> span.hasName("test")
                .hasAttributesSatisfyingExactly(
                    satisfies(
                        stringKey("couchbase.local.address"),
                        val -> assertThat(val).isNotNull()))));
  }

You would need to use val -> assertThat(val.actual()).isNotNull()) to get it to fail as expected, or more simply we can use AbstractAssert::isNotNull, like in:

  @Test
  void test() {
    testing().runWithSpan("test", () -> {});

    testing().waitAndAssertTraces(
        traceAssert -> traceAssert.hasSpansSatisfyingExactly(
            span -> span.hasName("test")
                .hasAttributesSatisfyingExactly(
                    satisfies(
                        stringKey("couchbase.local.address"),
                        AbstractAssert::isNotNull))));
  }

This PR cleans up all usages except couchbase, because the couchbase ones require a bit more of a refactor, so that will come in a followup.

[laurit]

You would need to use val -> assertThat(val.actual()).isNotNull()) to get it to fail as expected, or more simply we can use AbstractAssert::isNotNull

AbstractAssert::isNotNull is same as val -> val.isNotNull()

[trask]

val -> val.isNotNull()

this reads a bit better to me, @jaydeluca wdyt?

[jaydeluca]

val -> val.isNotNull()
this reads a bit better to me, @jaydeluca wdyt?

Intellij peer pressured me into the shorthand. i do think the other way reads better, i'll update it @trask