Removing lazy initialization behavior from MelScale

[mthrok]

As discussed in #1454, we are going to remove lazy initialization behavior from MelScale transform. This is a multi-release change. This issue tracks the changes.

Goal

1. Remove lazy initialization behavior from T.MelScale
2. Set a default value that aligns with Spectrogram.

Timeline

1. In release 0.9, we issue a warning when T.MelScale is constructed without valid value of n_stft, saying that the behavior is deprecated and will be removed in 0.10.
2. In release 0.10.0, we remove the code related to the lazy behavior.

Progress

1. [#1511] Add deprecation warning to MelScale for unset weight #1515 Add deprecation warning.
2. Remove lazy behavior from MelScale #1569 Remove the implementation.