Packaging: speed up el8 package build using zstd compression

There was a multi-minute difference between el8 and el9.
The compression algorithm is the only significant difference, so
I timed building the same el8 package with different algorithms.
- xz and lzma were the slowest at over 3 minutes.
- gzip and zstd were the fastest at under 1 minute (at any level).

The size differences were marginal, but zstd:best was the closest
match in size to xz, so I used that to keep the package size as
small as possible while speeding up the package build process.

Author: cognifloyd

packaging/BUILD

@@ -101,7 +101,8 @@ nfpm_rpm_package(
     vendor="The StackStorm Project",
     packager=_maintainer,
     # group="System/Management",  # was only useful for EL 5 and earlier
+    compression="zstd:best",  # xz and lzma are ~3x slower than gzip or zstd
     **_common_pkg_metadata,
-    **_distro("el8", compression="xz"),
-    **_distro("el9", compression="zstd:default"),
+    **_distro("el8"),
+    **_distro("el9"),
 )