1.6.1 Patch Release

[trivialfis]

We have a number of note-worthy fixes in JVM packages and categorical data support, including a fix for DeviceQuantileDMatrix in distributed environments, and support for barrier execution mode in the spark package to prevent potential hang during training.

• [jvm-packages] move the dmatrix building into rabit context #7823
• [doc] update the jvm tutorial to 1.6.1 [skip ci] #7834
• [Breaking][jvm-packages] add barrier execution mode #7836
• [doc] remove the doc about killing SparkContext [skip ci] #7840
• [jvm-packages] model loading should be compatible with old models #7845
• [jvm-package] remove the coalesce in barrier mode #7846
• Ignore all Java exceptions when looking for Linux musl support #7844

cc @wbo4958

[wbo4958]

@trivialfis Please also add #7845

[wbo4958]

@trivialfis Please also add #7846

[trivialfis]

Will make a patch release for Python as well for fixes in categorical data support.

[trivialfis]

@hcho3 I will submit the patch release for Python today. Could you please help with the JVM packages when you are available?

[trivialfis]

All Python packages are submitted.

[hcho3]

@trivialfis I'm submitting the JVM package today.