perf: pkg/util/mapz Enhancement (sub task of pkg/util Enhancement #833)

[jxs1211]

Pre-Checklist

Note: please complete ALL items in the following checklist.

• I have read through the CONTRIBUTING.md documentation.
• My code has the necessary comments and documentation (if needed).
• I have added relevant tests

Description

After investigation and testing, there is a place that could be improved for better performance.

Related Issues

see #833 for more details

New Behavior (screenshots if needed)

before improvement:

goos: linux
goarch: amd64
pkg: github.com/devstream-io/devstream/pkg/util/mapz
cpu: Intel(R) Xeon(R) CPU E5-1650 0 @ 3.20GHz
BenchmarkFillMapWithStrAndError-12         92894             13964 ns/op           10170 B/op          9 allocs/op
PASS
ok      github.com/devstream-io/devstream/pkg/util/mapz 2.378s

after improvement:

goos: linux
goarch: amd64
pkg: github.com/devstream-io/devstream/pkg/util/mapz
cpu: Intel(R) Xeon(R) CPU E5-1650 0 @ 3.20GHz
BenchmarkFillMapWithStrAndError-12        157182              6585 ns/op            5401 B/op          3 allocs/op
PASS
ok      github.com/devstream-io/devstream/pkg/util/mapz 1.130s

[xavier-hou]

@jxs1211 Many thanks to the unit test and performance imporvement!