Typo in OtlpLongTaskTImer

[shakuzen]

As pointed out by @jonatan-ivanov the class name has a typo https://github.com/micrometer-metrics/micrometer/pull/3129/files#diff-50a6ef44465b81afceb0f60b33a7a2bda3b56f26fd1273fb0ea1e62009a69d39

[shakuzen]

Already fixed in e0be5d3