util.Truncate not adding all values to the format string

[mmatache]

Describe the bug
util.Truncate function will return an incorrectly formatted string if the first format argument is long enough to remove the excess

To Reproduce
Steps to reproduce the behavior:

1. call `util.Truncate("%s-%s-collector", 63, "4d96-11ea-b174-c85b7644b6b5-5d0c1e62-4d96-11ea-b174-c85b7644b6b5", "d0c1e62")

Expected behavior
The following string should be generated: 4d96-11ea-b174-c85b7644b6b5-5d0c1e62-4d96-11e-d0c1e62-collector

Actual behavior
The following string is generated: 4d96-11ea-b174-c85b7644b6b5-5d0c1e62-4d96-11e-%!s(MISSING)-coll

The reason this does not directly affect users of Jaeger is that either the DNS formatting is always applied when this is called or that no users have had the long name issue.