fix(core): remove erroneous $ in flakiness overhead

[Malinskiy]

Flakiness overhead: 0H 01m 00s$ <- should not be there

[Malinskiy]

Closes #825

[codecov]

Codecov Report

Merging #826 (ddb7fcb) into develop (7873e5b) will not change coverage.
The diff coverage is 100.00%.

❗ Current head ddb7fcb differs from pull request most recent head 884b1a1. Consider uploading reports for the commit 884b1a1 to get more accurate results

@@            Coverage Diff             @@
##             develop     #826   +/-   ##
==========================================
  Coverage      59.62%   59.62%           
  Complexity       799      799           
==========================================
  Files            213      213           
  Lines           4384     4384           
  Branches         690      690           
==========================================
  Hits            2614     2614           
  Misses          1445     1445           
  Partials         325      325           

Files Changed	Coverage Δ
...malinskiy/marathon/report/stdout/StdoutReporter.kt	96.96% <100.00%> (ø)

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