[buildbot] phase1: workaround dlprune recursive directory removal

[LEDE Commits]

ynezz pushed a commit to buildbot.git, annotated tag v8:
https://git.openwrt.org/30e2e5d800a87aebd8a87a78812a4b527c56bf2f

commit 30e2e5d800a87aebd8a87a78812a4b527c56bf2f
Author: Petr Štetiar <ynezz at true.cz>
AuthorDate: Sat Jul 22 10:53:45 2023 +0200

    phase1: workaround dlprune recursive directory removal
    
    Workarounds following issue:
    
     find: cannot delete ‘dl/ath10k-ct-firmware-2020-11-08’: Directory not empty
    
    References: #13
    Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 phase1/master.cfg | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/phase1/master.cfg b/phase1/master.cfg
index 3080421..6f6c650 100644
--- a/phase1/master.cfg
+++ b/phase1/master.cfg
@@ -1037,6 +1037,9 @@ def prepareFactory(target):
             descriptionDone="dl/ pruned",
             command="find dl/ -mindepth 1 -atime +15 -delete -print",
             logEnviron=False,
+            haltOnFailure=False,
+            flunkOnFailure=False,
+            warnOnFailure=False,
         )
     )