Can't attach to self-contained .NET Core application (macOS)

Hi there,

I hope you can help me. I have a strange problem, just under macOS. Please have a look below for a detailed description.

Thanks for your help.

## Issue Description ##
## Steps to Reproduce ##
1. Publish .NET Core project as a self-contained application
2. Create a debug target in launch.json
{
"name": "Attach MyBackend",
"type": "coreclr",
"request": "attach",
"processName": "MyBackend",
}
3. Try to attach the running process. You will just get a message, that there is no process running with the given name.
4. If you attach the process by choosing it manually from the picking list, it will work.
The problem does not exist under Windows ("processName": "MyBackend.exe").

## Logs ##

### OmniSharp log ###
Post the output from Output-->OmniSharp log here

### C# log ###
Post the output from Output-->C# here

## Environment information ##

**VSCode version**: 1.34.0
**C# Extension**: 1.19.1

Mono Information
OmniSharp using global mono :5.16.0
Dotnet Information
.NET Core SDK (reflecting any global.json):
Version: 2.2.104
Commit: 73f036d4ac

Runtime Environment:
OS Name: Mac OS X
OS Version: 10.14
OS Platform: Darwin
RID: osx.10.14-x64
Base Path: /usr/local/share/dotnet/sdk/2.2.104/

Host (useful for support):
Version: 2.2.2
Commit: a4fd7b2c84

.NET Core SDKs installed:
2.2.104 [/usr/local/share/dotnet/sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.2.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.2.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

Visual Studio Code Extensions

|Extension|Author|Version|
|---|---|---|
|csharp|ms-vscode|1.19.1|
|debugger-for-chrome|msjsdiag|4.11.3|
|gitlens|eamodio|9.8.1|
|gulptasks|nickdodd79|1.3.1|
|vscode-versionlens|pflannery|0.23.0|;