fix(logging): Clean up extra empty spaces when redirectLogger is used

[zmyzheng]

Summary

This PR removes the extra spaces in logging when redirectLogger is used.

• 3 spaces between the timestamp and log level
• 3 or 4 spaces between the log level and log messages
• 2 spaces between prefix and attrMsg

Example log contents:

The fix includes 3 aspects:

1. Based on fmt.Println func's definition, spaces are always added between operands. Because of this, adding " " among ts.In(time.UTC).Format(time.RFC3339) , level.Indicator() and prefix + attrMsg will cause extra spaces to be generated (3 spaces rather than 1 space). This PR removes the " " among them.

2. When prefix is not empty, a space is added behind ]:

At the same time, another space is added in front of (:

Because of this, 2 spaces are added between prefix and attrMsg:

This PR removes one space between them.

3. When both prefix and attrMsg are empty, adding prefix + attrMsg into msg will cause the empty string of prefix + attrMsg being wrapped by 2 extra empty spaces:
   

This PR updates the logic to only add prefix + attrMsg into msg if it is not empty

Note: the above issues only appears whenredirectLogger is used.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #16254

[telegraf-tiger]

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Artifact URLs

DEB	RPM	TAR GZ	ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

[srebhan]

@zmyzheng thanks for your contribution! I do have two small questions in the code...

[srebhan]

Thanks for your contribution and your thorough explanation!