Do not check in StewardPlugin if dependencies are defined in build files

This reverts #584 which shouldn't be needed any more since #1188.

The goal of #584 was to ignore dependencies that are added by plugins
because those dependencies cannot be updated. Unfortunately this
solution is brittle because it also ignores plugins that are added via
`addSbtPlugin` in `settings`, see http4s/sbt-http4s-org#26 (comment).
(They also have a source position like ` LinePosition(Defaults.scala,...)`.)

A similar optimization was later added in #1188 which ignores all
dependencies whose versions number cannot be found in files of the repo.
This optimization also covers dependencies that are added by plugins.
Let's see if this is good enough to also cover #584.

modules/sbt-plugin/src/main/scala/org/scalasteward/sbt/plugin/StewardPlugin.scala

@@ -17,9 +17,8 @@
 package org.scalasteward.sbt.plugin
 
 import sbt.Keys._
-import sbt.{Def, _}
+import sbt._
 import scala.util.Try
-import scala.util.matching.Regex
 
 object StewardPlugin extends AutoPlugin {
  override def trigger: PluginTrigger = allRequirements
@@ -35,14 +34,11 @@ object StewardPlugin extends AutoPlugin {
  Seq(
  stewardDependencies := {
  val log = streams.value.log
- val sourcePositions = dependencyPositions.value
- val buildRoot = baseDirectory.in(ThisBuild).value
  val scalaBinaryVersionValue = scalaBinaryVersion.value
  val scalaVersionValue = scalaVersion.value
  val sbtCredentials = findCredentials.value
 
  val libraryDeps = libraryDependencies.value
- .filter(isDefinedInBuildFiles(_, sourcePositions, buildRoot))
  .map(moduleId => toDependency(moduleId, scalaVersionValue, scalaBinaryVersionValue))
 
  val scalafixDeps = findScalafixDependencies.value
@@ -80,44 +76,6 @@ object StewardPlugin extends AutoPlugin {
  }
  )
 
- // Inspired by https://github.com/rtimush/sbt-updates/issues/42 and
- // https://github.com/rtimush/sbt-updates/pull/112
- private def isDefinedInBuildFiles(
- moduleId: ModuleID,
- sourcePositions: Map[ModuleID, SourcePosition],
- buildRoot: File
- ): Boolean =
- sourcePositions.get(moduleId) match {
- case Some(fp: FilePosition) =>
- val path = fp.path
- () match {
- case _ if path.startsWith("(sbt.Classpaths") => true
- case _ if path.startsWith("(") =>
- extractFileName(path).exists(fileExists(buildRoot, _))
-
- // Compiler plugins added via addCompilerPlugin(...) have a SourcePosition
- // like this: LinePosition(Defaults.scala,3738).
- case _ if path.startsWith("Defaults.scala") && isCompilerPlugin(moduleId) => true
- case _ if path.startsWith("Defaults.scala") => false
- case _ => true
- }
- case _ => true
- }
-
- private def extractFileName(path: String): Option[String] = {
- val FileNamePattern: Regex = "^\\([^\\)]+\\) (.*)$".r
- path match {
- case FileNamePattern(fileName) => Some(fileName)
- case _ => None
- }
- }
-
- private def fileExists(buildRoot: File, file: String): Boolean =
- (buildRoot / "project" / file).exists()
-
- private def isCompilerPlugin(moduleId: ModuleID): Boolean =
- moduleId.configurations.exists(_ == "plugin->default(compile)")
-
  // base on mdoc
  // https://github.com/scalameta/mdoc/blob/62cacfbc4c7b618228e349d4f460061916398424/mdoc-sbt/src/main/scala/mdoc/MdocPlugin.scala#L164-L182
  lazy val findScalafixDependencies: Def.Initialize[Option[Seq[ModuleID]]] = Def.settingDyn {