Upgrade to Lucene-7.4.0-snapshot-bcf9f5c36b (#29490)

This snapshot includes LUCENE-8246 which allows to customize the number
of deletes a merge claims

Author: dnhatn

buildSrc/version.properties

@@ -1,5 +1,5 @@
 elasticsearch     = 6.3.0
-lucene            = 7.4.0-snapshot-2b27dd846a
+lucene            = 7.4.0-snapshot-bcf9f5c36b
 
 # optional dependencies
 spatial4j         = 0.7

modules/lang-expression/licenses/lucene-expressions-7.4.0-snapshot-2b27dd846a.jar.sha1

@@ -0,0 +1 @@
+c78657977dd5ca44defbdd77155b87e199d607b7

modules/lang-expression/licenses/lucene-expressions-7.4.0-snapshot-bcf9f5c36b.jar.sha1

@@ -0,0 +1 @@
+946cfdd6f93e542094fde179c854f915097a24ee

plugins/analysis-icu/licenses/lucene-analyzers-icu-7.4.0-snapshot-2b27dd846a.jar.sha1

@@ -0,0 +1 @@
+3be7d940a7f9f0b090b07d40095bf1dfbce4c0b4

plugins/analysis-icu/licenses/lucene-analyzers-icu-7.4.0-snapshot-bcf9f5c36b.jar.sha1

@@ -0,0 +1 @@
+aa1d1419a71c51af0fe07c85565f931655b50d2d