Remove refs to scala-xml in shell scripts

[michelou]

This PR is a follow-up of #5597.

Additional question about the modified file dist\bin\dotc:
Why does the variable $DOTTY_LIB appear twice in toolchain construction (I would remove the 1st occurence) ?!

  toolchain=""
  toolchain+="$SCALA_LIB$PSEP"
  toolchain+="$DOTTY_LIB$PSEP"
  toolchain+="$SCALA_ASM$PSEP"
  toolchain+="$SBT_INTF$PSEP"
  toolchain+="$DOTTY_INTF$PSEP"
  toolchain+="$DOTTY_LIB$PSEP"
  toolchain+="$DOTTY_COMP$PSEP"

For comparison, I don't have the repetition in the corresponding batch file dist\bin\dotc.bat (PR #5444):

set __TOOLCHAIN=%_SCALA_LIB%%_PSEP%
set __TOOLCHAIN=%__TOOLCHAIN%%_SCALA_ASM%%_PSEP%
set __TOOLCHAIN=%__TOOLCHAIN%%_SBT_INTF%%_PSEP%
set __TOOLCHAIN=%__TOOLCHAIN%%_DOTTY_INTF%%_PSEP%
set __TOOLCHAIN=%__TOOLCHAIN%%_DOTTY_LIB%%_PSEP%
set __TOOLCHAIN=%__TOOLCHAIN%%_DOTTY_COMP%%_PSEP%

[dottybot]

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[liufengyun]

@michelou Thanks for the catch. I think it's a typo, we should remove the duplicate path.

[liufengyun]

LGTM