[builds] fix build_in_docker scripts (#5688)

* ignore bin/obj folders in docker

* fix powershell syntax error

* stop the ps1 script on errors

* no need to change directory

* oops

tracer/build/_build/.dockerignore

@@ -0,0 +1,3 @@
+**/bin/
+**/obj/
+**/*.user

tracer/build_in_docker.ps1

@@ -4,8 +4,7 @@ Param(
  [string[]]$BuildArguments
 )
 
-# in case we are being run from outside this directory
-Set-Location $PSScriptRoot
+$ErrorActionPreference = "Stop"
 
 $ROOT_DIR="$PSScriptRoot/.."
 $BUILD_DIR="$ROOT_DIR/tracer/build/_build"
@@ -18,7 +17,7 @@ $IMAGE_NAME="dd-trace-dotnet/alpine-base"
  "$BUILD_DIR"
 
 &docker run -it --rm `
- --mount type=bind,source="$ROOT_DIR",target=/project `
+ --mount "type=bind,source=$ROOT_DIR,target=/project" `
  --env NugetPackageDirectory=/project/packages `
  --env artifacts=/project/tracer/bin/artifacts `
  --env DD_INSTRUMENTATION_TELEMETRY_ENABLED=0 `

tracer/build_in_docker.sh

@@ -1,10 +1,8 @@
 #!/usr/bin/env bash
 set -euox pipefail
 
-# in case we are being run from outside this directory
-cd "$(dirname "$0")"
-
-ROOT_DIR="$(dirname $(pwd))"
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+ROOT_DIR="$(dirname -- "$SCRIPT_DIR" )"
 BUILD_DIR="$ROOT_DIR/tracer/build/_build"
 IMAGE_NAME="dd-trace-dotnet/alpine-base"