fix: remove duplicated initialization of rand

[ulbqb]

Description

This PR removes duplicated initialization of rand.

Issue

ostracon/libs/rand/random.go

Lines 29 to 38 in 08c34d4

	func init() {
	grand = NewRand()
	grand.init()
	}
	func NewRand() *Rand {
	rand := &Rand{}
	rand.init()
	return rand
	}

rand.init() is run twice on init().

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.54%. Comparing base (2aa7d4c) to head (c4c4864).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #764      +/-   ##
==========================================
- Coverage   66.54%   66.54%   -0.01%     
==========================================
  Files         285      285              
  Lines       37919    37918       -1     
==========================================
- Hits        25232    25231       -1     
+ Misses      10883    10880       -3     
- Partials     1804     1807       +3     

Files	Coverage Δ
libs/rand/random.go	65.66% <ø> (-0.21%)	⬇️

... and 10 files with indirect coverage changes